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Mastering Blockchain
Mastering Blockchain

Mastering Blockchain: A deep dive into distributed ledgers, consensus protocols, smart contracts, DApps, cryptocurrencies, Ethereum, and more , Third Edition

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Mastering Blockchain

Decentralization

Decentralization is not a new concept. It has been in use in strategy, management, and government for a long time. The basic idea of decentralization is to distribute control and authority to the peripheries of an organization instead of one central body being in full control of the organization. This configuration produces several benefits for organizations, such as increased efficiency, expedited decision making, better motivation, and a reduced burden on top management.

In this chapter, the concept of decentralization will be discussed in the context of blockchain. The fundamental basis of blockchain is that no single central authority is in control of the network. This chapter will present examples of various methods of decentralization and ways to achieve it. Furthermore, the decentralization of the blockchain ecosystem, decentralized applications, and platforms for achieving decentralization will be discussed in detail. Many exciting applications and ideas emerge from the decentralized blockchain technology, such as decentralized finance and decentralized identity, which will be introduced in this chapter.

Decentralization using blockchain

Decentralization is a core benefit and service provided by blockchain technology. By design, blockchain is a perfect vehicle for providing a platform that does not need any intermediaries and that can function with many different leaders chosen via consensus mechanisms. This model allows anyone to compete to become the decision-making authority. A consensus mechanism governs this competition, and the most famous method is known as Proof of Work (PoW).

Decentralization is applied in varying degrees from a semi-decentralized model to a fully decentralized one depending on the requirements and circumstances. Decentralization can be viewed from a blockchain perspective as a mechanism that provides a way to remodel existing applications and paradigms, or to build new applications, to give full control to users.

Information and communication technology (ICT) has conventionally been based on a centralized paradigm whereby database or application servers are under the control of a central authority, such as a system administrator. With Bitcoin and the advent of blockchain technology, this model has changed, and now the technology exists to allow anyone to start a decentralized system and operate it with no single point of failure or single trusted authority. It can either be run autonomously or by requiring some human intervention, depending on the type and model of governance used in the decentralized application running on the blockchain.

The following diagram shows the different types of systems that currently exist: central, distributed, and decentralized. This concept was first published by Paul Baran in On Distributed Communications: I. Introduction to Distributed Communications Networks (Rand Corporation, 1964):

C:\Users\suzannec\Desktop\B09700_02_01.png

Figure 2.1: Different types of networks/systems

Centralized systems are conventional (client-server) IT systems in which there is a single authority that controls the system, and who is solely in charge of all operations on the system. All users of a centralized system are dependent on a single source of service. The majority of online service providers, including Google, Amazon, eBay, and Apple's App Store, use this conventional model to deliver services.

In a distributed system, data and computation are spread across multiple nodes in the network. Sometimes, this term is confused with parallel computing. While there is some overlap in the definition, the main difference between these systems is that in a parallel computing system, computation is performed by all nodes simultaneously in order to achieve the result; for example, parallel computing platforms are used in weather research and forecasting, simulation, and financial modeling. On the other hand, in a distributed system, computation may not happen in parallel and data is replicated across multiple nodes that users view as a single, coherent system. Variations of both of these models are used to achieve fault tolerance and speed. In the parallel system model, there is still a central authority that has control over all nodes and governs processing. This means that the system is still centralized in nature.

The critical difference between a decentralized system and distributed system is that in a distributed system, there is still a central authority that governs the entire system, whereas in a decentralized system, no such authority exists.

A decentralized system is a type of network where nodes are not dependent on a single master node; instead, control is distributed among many nodes. This is analogous to a model where each department in an organization is in charge of its own database server, thus taking away the power from the central server and distributing it to the sub-departments, who manage their own databases.

A significant innovation in the decentralized paradigm that has given rise to this new era of decentralization of applications is decentralized consensus. This mechanism came into play with Bitcoin, and it enables a user to agree on something via a consensus algorithm without the need for a central, trusted third party, intermediary, or service provider.

We can also now view the different types of networks shown earlier from a different perspective, where we highlight the controlling authority of these networks as a symbolic hand, as shown in the following diagram. This model provides a clearer understanding of the differences between these networks from a decentralization point of view:

Figure 2.2: Different types of networks/systems depicting decentralization from a modern perspective

The preceding diagram shows that the centralized model is the traditional one in which a central controller exists, and it can be viewed as a depiction of the usual client/server model. In the middle we have distributed systems, where we still have a central controller but the system comprises many dispersed nodes. On the right-hand side, notice that there is no hand/controller controlling the networks.

This is the key difference between decentralized and distributed networks. A decentralized system may look like a distributed system from a topological point of view, but it doesn't have a central authority that controls the network.

The differences between distributed and decentralized systems can also be viewed at a practical level in the following diagrams:

Figure 2.3: A traditional distributed system comprises many servers performing different roles

The following diagram shows a decentralized system (based on blockchain) where an exact replica of the applications and data is maintained across the entire network on each participating node:

Figure 2.4: A blockchain-based decentralized system (notice the direct P2P connections and the exact replicas of blocks)

A comparison between centralized and decentralized systems (networks/applications) is shown in the following table:

Feature

Centralized

Decentralized

Ownership

Service provider

All users

Architecture

Client/server

Distributed, different topologies

Security

Basic

More secure

High availability

No

Yes

Fault tolerance

Basic, single point of failure

Highly tolerant, as service is replicated

Collusion resistance

Basic, because it's under the control of a group or even single individual

Highly resistant, as consensus algorithms ensure defense against adversaries

Application architecture

Single application

Application replicated across all nodes on the network

Trust

Consumers have to trust the service provider

No mutual trust required

Cost for consumer

Higher

Lower

The comparison in the table only covers some main features and is not an exhaustive list of all features. There may be other features of interest that can be compared too, but this list should provide a good level of comparison.

Now we will discuss what methods can be used to achieve decentralization.

Methods of decentralization

Two methods can be used to achieve decentralization: disintermediation and competition. These methods will be discussed in detail in the sections that follow.

Disintermediation

The concept of disintermediation can be explained with the aid of an example. Imagine that you want to send money to a friend in another country. You go to a bank, which, for a fee, will transfer your money to the bank in that country. In this case, the bank maintains a central database that is updated, confirming that you have sent the money. With blockchain technology, it is possible to send this money directly to your friend without the need for a bank. All you need is the address of your friend on the blockchain. This way, the intermediary (that is, the bank) is no longer required, and decentralization is achieved by disintermediation. It is debatable, however, how practical decentralization through disintermediation is in the financial sector due to the massive regulatory and compliance requirements. Nevertheless, this model can be used not only in finance but in many other industries as well, such as health, law, and the public sector. In the health industry, where patients, instead of relying on a trusted third party (such as the hospital record system) can be in full control of their own identity and their data that they can share directly with only those entities that they trust. As a general solution, blockchain can serve as a decentralized health record management system where health records can be exchanged securely and directly between different entities (hospitals, pharmaceutical companies, patients) globally without any central authority.

Contest-driven decentralization

In the method involving competition, different service providers compete with each other in order to be selected for the provision of services by the system. This paradigm does not achieve complete decentralization. However, to a certain degree, it ensures that an intermediary or service provider is not monopolizing the service. In the context of blockchain technology, a system can be envisioned in which smart contracts can choose an external data provider from a large number of providers based on their reputation, previous score, reviews, and quality of service.

This method will not result in full decentralization, but it allows smart contracts to make a free choice based on the criteria just mentioned. This way, an environment of competition is cultivated among service providers where they compete with each other to become the data provider of choice.

In the following diagram, varying levels of decentralization are shown. On the left side, the conventional approach is shown where a central system is in control; on the right side, complete disintermediation is achieved, as intermediaries are entirely removed. Competing intermediaries or service providers are shown in the center. At that level, intermediaries or service providers are selected based on reputation or voting, thus achieving partial decentralization:

Figure 2.5: Scale of decentralization

There are many benefits of decentralization, including transparency, efficiency, cost saving, development of trusted ecosystems, and in some cases privacy and anonymity. Some challenges, such as security requirements, software bugs, and human error, need to be examined thoroughly.

For example, in a decentralized system such as Bitcoin or Ethereum where security is normally provided by private keys, how can we ensure that an asset or a token associated with these private keys cannot be rendered useless due to negligence or bugs in the code? What if the private keys are lost due to user negligence? What if due to a bug in the smart contract code the decentralized application becomes vulnerable to attack?

Before embarking on a journey to decentralize everything using blockchain and decentralized applications, it is essential that we understand that not everything can or needs to be decentralized.

This view raises some fundamental questions. Is a blockchain really needed? When is a blockchain required? In what circumstances is blockchain preferable to traditional databases? To answer these questions, go through the simple set of questions presented below:

Question

Yes/No

Recommended solution

Is high data throughput required?

Yes

Use a traditional database.

No

A central database might still be useful if other requirements are met. For example, if users trust each other, then perhaps there is no need for a blockchain. However, if they don't or trust cannot be established for any reason, blockchain can be helpful.

Are updates centrally controlled?

Yes

Use a traditional database.

No

You may investigate how a public/private blockchain can help.

Do users trust each other?

Yes

Use a traditional database.

No

Use a public blockchain.

Are users anonymous?

Yes

Use a public blockchain.

No

Use a private blockchain.

Is consensus required to be maintained within a consortium?

Yes

Use a private blockchain.

No

Use a public blockchain.

Is strict data immutability required?

Yes

Use a blockchain.

No

Use a central/traditional database.

Answering all of these questions can help you decide whether or not a blockchain is required or suitable for solving the problem. Beyond the questions posed in this model, there are many other issues to consider, such as latency, choice of consensus mechanisms, whether consensus is required or not, and where consensus is going to be achieved. If consensus is maintained internally by a consortium, then a private blockchain should be used; otherwise, if consensus is required publicly among multiple entities, then a public blockchain solution should be considered. Other aspects, such as immutability, should also be considered when deciding whether to use a blockchain or a traditional database. If strict data immutability is required, then a public blockchain should be used; otherwise, a central database may be an option.

As blockchain technology matures, there will be more questions raised regarding this selection model. For now, however, this set of questions is sufficient for deciding whether a blockchain-based solution is suitable or not.

Now we understand different methods of decentralization and have looked at how to decide whether a blockchain is required or not in a particular scenario. Let's now look at the process of decentralization, that is, how we can take an existing system and decentralize it. First, we'll briefly look at the different ways to achieve decentralization.

Routes to decentralization

There are systems that pre-date blockchain and Bitcoin, including BitTorrent and the Gnutella file-sharing system, which to a certain degree could be classified as decentralized, but due to a lack of any incentivization mechanism, participation from the community gradually decreased. There wasn't any incentive to keep the users interested in participating in the growth of the network. With the advent of blockchain technology, many initiatives are being taken to leverage this new technology to achieve decentralization. The Bitcoin blockchain is typically the first choice for many, as it has proven to be the most resilient and secure blockchain and has a market cap of nearly $166 billion at the time of writing. Alternatively, other blockchains, such as Ethereum, serve as the tool of choice for many developers for building decentralized applications. Compared to Bitcoin, Ethereum has become a more prominent choice because of the flexibility it allows for programming any business logic into the blockchain by using smart contracts.

How to decentralize

Arvind Narayanan and others have proposed a framework in their book Bitcoin and Cryptocurrency Technologies that can be used to evaluate the decentralization requirements of a variety of issues in the context of blockchain technology. The framework raises four questions whose answers provide a clear understanding of how a system can be decentralized:

  1. What is being decentralized?
  2. What level of decentralization is required?
  3. What blockchain is used?
  4. What security mechanism is used?

The first question simply asks you to identify what system is being decentralized. This can be any system, such as an identity system or a trading system.

The second question asks you to specify the level of decentralization required by examining the scale of decentralization, as discussed earlier. It can be full disintermediation or partial disintermediation.

The third question asks developers to determine which blockchain is suitable for a particular application. It can be Bitcoin blockchain, Ethereum blockchain, or any other blockchain that is deemed fit for the specific application.

Finally, a fundamental question that needs to be addressed is how the security of a decentralized system will be guaranteed. For example, the security mechanism can be atomicity-based, where either the transaction executes in full or does not execute at all. This deterministic approach ensures the integrity of the system. Other mechanisms may include one based on reputation, which allows for varying degrees of trust in a system.

In the following section, let's evaluate a money transfer system as an example of an application selected to be decentralized.

Decentralization framework example

The four questions discussed previously are used to evaluate the decentralization requirements of this application. The answers to these questions are as follows:

  1. Money transfer system
  2. Disintermediation
  3. Bitcoin
  4. Atomicity

The responses indicate that the money transfer system can be decentralized by removing the intermediary, implemented on the Bitcoin blockchain, and that a security guarantee will be provided via atomicity. Atomicity will ensure that transactions execute successfully in full or do not execute at all. We have chosen the Bitcoin blockchain because it is the longest established blockchain and has stood the test of time.

Similarly, this framework can be used for any other system that needs to be evaluated in terms of decentralization. The answers to these four simple questions help clarify what approach to take to decentralize the system.

To achieve complete decentralization, it is necessary that the environment around the blockchain also be decentralized. We'll look at the full ecosystem of decentralization next.

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Key benefits

  • Updated with four new chapters on consensus algorithms, Ethereum 2.0, tokenization, and enterprise blockchains
  • Learn about key elements of blockchain theory such as decentralization, cryptography, and consensus protocols
  • Get to grips with Solidity, Web3, cryptocurrencies, smart contract development and solve scalability, security and privacy issues
  • Discover the architecture of different distributed ledger platforms including Ethereum, Bitcoin, Hyperledger Fabric, Hyperledger Sawtooth, Corda and Quorum

Description

Blockchain is the backbone of cryptocurrencies, with applications in finance, government, media, and other industries. With a legacy of providing technologists with executable insights, this new edition of Mastering Blockchain is thoroughly revised and updated to the latest blockchain research with four new chapters on consensus algorithms, Serenity (the update that will introduce Ethereum 2.0), tokenization, and enterprise blockchains. This book covers the basics, including blockchain’s technical underpinnings, cryptography and consensus protocols. It also provides you with expert knowledge on decentralization, decentralized application development on Ethereum, Bitcoin, alternative coins, smart contracts, alternative blockchains, and Hyperledger. Further, you will explore blockchain solutions beyond cryptocurrencies such as the Internet of Things with blockchain, enterprise blockchains, tokenization using blockchain, and consider the future scope of this fascinating and disruptive technology. By the end of this book, you will have gained a thorough comprehension of the various facets of blockchain and understand their potential in diverse real-world scenarios.

Who is this book for?

If you are a technologist, business executive, a student or an enthusiast who wishes to explore the fascinating world of blockchain technology, smart contracts, decentralized applications and distributed systems then this book is for you. Basic familiarity with a beginner-level command of a programming language would be a plus.

What you will learn

  • Grasp the mechanisms behind Bitcoin, Ethereum, and alternative cryptocurrencies
  • Understand cryptography and its usage in blockchain
  • Understand the theoretical foundations of smart contracts
  • Develop decentralized applications using Solidity, Remix, Truffle, Ganache and Drizzle
  • Identify and examine applications of blockchain beyond cryptocurrencies
  • Understand the architecture and development of Ethereum 2.0
  • Explore research topics and the future scope of blockchain
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Table of Contents

23 Chapters
Blockchain 101 Chevron down icon Chevron up icon
Decentralization Chevron down icon Chevron up icon
Symmetric Cryptography Chevron down icon Chevron up icon
Public Key Cryptography Chevron down icon Chevron up icon
Consensus Algorithms Chevron down icon Chevron up icon
Introducing Bitcoin Chevron down icon Chevron up icon
The Bitcoin Network and Payments Chevron down icon Chevron up icon
Bitcoin Clients and APIs Chevron down icon Chevron up icon
Alternative Coins Chevron down icon Chevron up icon
Smart Contracts Chevron down icon Chevron up icon
Ethereum 101 Chevron down icon Chevron up icon
Further Ethereum Chevron down icon Chevron up icon
Ethereum Development Environment Chevron down icon Chevron up icon
Development Tools and Frameworks Chevron down icon Chevron up icon
Introducing Web3 Chevron down icon Chevron up icon
Serenity Chevron down icon Chevron up icon
Hyperledger Chevron down icon Chevron up icon
Tokenization Chevron down icon Chevron up icon
Blockchain – Outside of Currencies Chevron down icon Chevron up icon
Enterprise Blockchain Chevron down icon Chevron up icon
Scalability and Other Challenges Chevron down icon Chevron up icon
Current Landscape and What's Next Chevron down icon Chevron up icon
Index Chevron down icon Chevron up icon

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hawkinflight Oct 30, 2020
Full star icon Full star icon Full star icon Full star icon Full star icon 5
I am new to Blockchain, and I looked at this book to get an introduction. The first chapter, Blockchain 101, provides an excellent start and quickly presents a graph from which a prediction can be extrapolated, "blockchain will progress to become a mature technology by 2025". It answers the questions: why blockchain? "decentralized trust, security, cost savings, transparency, and efficiency" And, what are the challenges being researched? "scalability and privacy". Simply, it states: blockchain is a "decentralized-distributed system". An interesting history is given, blockchain was introduced with Bitcoin in 2008, and a long list of technologies, starting in the 1960's, is given which contributed to the development of Bitcoin. An improvement on the earlier technologies, the Bitcoin blockchain provides the ability to "prevent double spending in a completely trustless or permissionless environment", and it also "solves the SMR problem (probabilistically)". This is a great chapter, a very nice set-up! Further details are given, including of consensus, which provides the "decentralization of control through mining", and mining is used to "add more blocks to the blockchain".I enjoyed the chapter, Blockchain - Outside of Currencies. IoT is described as the "most prominent and most ready candidate for adapting blockchain technology". Interestingly, it is mentioned that the finance sector is exploring uses of blockchain with "high energy and enthusiasm"; however, "it is still far away from production-ready, blockchain-based systems".One of the chapters new to this edition of the book, Enterprise Blockchains, informs that "current public blockchains are not necessarily a suitable choice for enterprise use cases". Enterprise blockchains need faster performance, access governance, privacy, deterministic rather than probabilistic consensus algorithms, and to eliminate the need to have cryptocurrency on hand for transaction fees. It is mentioned that Corda (which is not really a blockchain) and Quorum are production-ready projects built on enterprise blockchains.The chapter on "Scalability and Challenges" addresses changes that need to be made to make the technology more adoptable, with the two most important being: performance on a large scale and privacy. Other issues include regulation, integration, interoperability, adaptability, and security, even though security is quite good already with Bitcoin.In the final chapter on the Current Landscape and What's Next, it is mentioned that there is a current inclination towards making use of an existing blockchain platform with only one application in mind for a specific industry, and these are called: application-specific blockchains (ASBCs). Currently, many start-ups are working on blockchain projects, and research is taking place in both academia and industry, in software and hardware. When it was discovered that methods were no longer efficient, focus shifted to optimizing and developing hardware. New programming languages are being developed for developing smart contracts. Blockchain as a Service (BaaS) is being offered in the cloud by Microsoft and IBM. Blockchain can beneficially converge with other technologies such as IoT and AI. It's mentioned that there are some debatable issues: public vs. private on the blockchain and central bank digital currency. There are some areas to address: regulation, illegal activity, and privacy or transparency. A really interesting list of 16 predictions expected to occur between 2020-2050 is given; for example, 1) The IoT will run on multiple blockchains and will give rise to an M2M economy. This will include energy devices, autonomous cars, and household accessories. 2) Central bank-issued digital currencies will become a reality, and will be applied in day-to-day use within the next two to five years. ...As a final note, it is mentioned that "blockchains are becoming intertwined with our lives just as the internet has been for decades" and "blockchain can arguably be considered the most innovative technology of this decade".This is a very nice, high quality book, which can help you jump on board.
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Amazon Customer Nov 30, 2020
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Nice book with deep insights
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Liz Valeo Mar 11, 2021
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2 inches thick and very well organized. Recommend highly as an in depth guide to blockchain at all skill levels.
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Fanta May 13, 2021
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Un tour de force attraverso la tecnologia blockchain, le criptovalute e gli smart contract, strumenti e piattaforme. Va nel dettaglio quanto necessario per chi ambisce a contribuire allo sviluppo della piattaforma (core blockchain) o allo sviluppo di applicazioni distribuite. Chiaro e bene illustrato. Livello di dettaglio decisamente eccessivo per chi vuole solo una panoramica dell'argomento (che puo' essere meglio servito da video su YouTube).
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Stefan Apr 16, 2022
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Outstanding introduction to Blockchain, covering all relevant aspects. Must read!
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Cancellation Policy for Published Printed Books:

You can cancel any order within 1 hour of placing the order. Simply contact customercare@packt.com with your order details or payment transaction id. If your order has already started the shipment process, we will do our best to stop it. However, if it is already on the way to you then when you receive it, you can contact us at customercare@packt.com using the returns and refund process.

Please understand that Packt Publishing cannot provide refunds or cancel any order except for the cases described in our Return Policy (i.e. Packt Publishing agrees to replace your printed book because it arrives damaged or material defect in book), Packt Publishing will not accept returns.

What is your returns and refunds policy? Chevron down icon Chevron up icon

Return Policy:

We want you to be happy with your purchase from Packtpub.com. We will not hassle you with returning print books to us. If the print book you receive from us is incorrect, damaged, doesn't work or is unacceptably late, please contact Customer Relations Team on customercare@packt.com with the order number and issue details as explained below:

  1. If you ordered (eBook, Video or Print Book) incorrectly or accidentally, please contact Customer Relations Team on customercare@packt.com within one hour of placing the order and we will replace/refund you the item cost.
  2. Sadly, if your eBook or Video file is faulty or a fault occurs during the eBook or Video being made available to you, i.e. during download then you should contact Customer Relations Team within 14 days of purchase on customercare@packt.com who will be able to resolve this issue for you.
  3. You will have a choice of replacement or refund of the problem items.(damaged, defective or incorrect)
  4. Once Customer Care Team confirms that you will be refunded, you should receive the refund within 10 to 12 working days.
  5. If you are only requesting a refund of one book from a multiple order, then we will refund you the appropriate single item.
  6. Where the items were shipped under a free shipping offer, there will be no shipping costs to refund.

On the off chance your printed book arrives damaged, with book material defect, contact our Customer Relation Team on customercare@packt.com within 14 days of receipt of the book with appropriate evidence of damage and we will work with you to secure a replacement copy, if necessary. Please note that each printed book you order from us is individually made by Packt's professional book-printing partner which is on a print-on-demand basis.

What tax is charged? Chevron down icon Chevron up icon

Currently, no tax is charged on the purchase of any print book (subject to change based on the laws and regulations). A localized VAT fee is charged only to our European and UK customers on eBooks, Video and subscriptions that they buy. GST is charged to Indian customers for eBooks and video purchases.

What payment methods can I use? Chevron down icon Chevron up icon

You can pay with the following card types:

  1. Visa Debit
  2. Visa Credit
  3. MasterCard
  4. PayPal
What is the delivery time and cost of print books? Chevron down icon Chevron up icon

Shipping Details

USA:

'

Economy: Delivery to most addresses in the US within 10-15 business days

Premium: Trackable Delivery to most addresses in the US within 3-8 business days

UK:

Economy: Delivery to most addresses in the U.K. within 7-9 business days.
Shipments are not trackable

Premium: Trackable delivery to most addresses in the U.K. within 3-4 business days!
Add one extra business day for deliveries to Northern Ireland and Scottish Highlands and islands

EU:

Premium: Trackable delivery to most EU destinations within 4-9 business days.

Australia:

Economy: Can deliver to P. O. Boxes and private residences.
Trackable service with delivery to addresses in Australia only.
Delivery time ranges from 7-9 business days for VIC and 8-10 business days for Interstate metro
Delivery time is up to 15 business days for remote areas of WA, NT & QLD.

Premium: Delivery to addresses in Australia only
Trackable delivery to most P. O. Boxes and private residences in Australia within 4-5 days based on the distance to a destination following dispatch.

India:

Premium: Delivery to most Indian addresses within 5-6 business days

Rest of the World:

Premium: Countries in the American continent: Trackable delivery to most countries within 4-7 business days

Asia:

Premium: Delivery to most Asian addresses within 5-9 business days

Disclaimer:
All orders received before 5 PM U.K time would start printing from the next business day. So the estimated delivery times start from the next day as well. Orders received after 5 PM U.K time (in our internal systems) on a business day or anytime on the weekend will begin printing the second to next business day. For example, an order placed at 11 AM today will begin printing tomorrow, whereas an order placed at 9 PM tonight will begin printing the day after tomorrow.


Unfortunately, due to several restrictions, we are unable to ship to the following countries:

  1. Afghanistan
  2. American Samoa
  3. Belarus
  4. Brunei Darussalam
  5. Central African Republic
  6. The Democratic Republic of Congo
  7. Eritrea
  8. Guinea-bissau
  9. Iran
  10. Lebanon
  11. Libiya Arab Jamahriya
  12. Somalia
  13. Sudan
  14. Russian Federation
  15. Syrian Arab Republic
  16. Ukraine
  17. Venezuela