Decentralized application overview

A decentralized application (or DApp) is an application that uses smart contracts to run. Smart contracts are deployed on the Ethereum virtual machine (EVM). It is similar to a client-server low-tier architecture. A DApp can have a frontend (web) that makes calls to its backend (smart contract) through the web3.js API.

 

The following structure is what we are going to build for our crowdfunding DApp:

Strucuture of what we will be building for crowdfunding DApp

web3.js quick overview

web3.js is an Ethereum JavaScript API, that provides a collection of libraries to interact with a local or remote Ethereum network. The connection between web3js and Ethereum is made by using the HTTP or IPC protocol. In the following table, we quickly review a number of important web3.js API concepts:

API reference	Description	Example
web3-eth	This package provides an API to interact with the Ethereum blockchain and smart contracts	getBalance, sendTransaction, coinbase, getBlockNumber...