C# has been one of the most dynamic languages in recent times. This language is open source and mostly driven by a group of software engineers, who recently came up with lots of major changes to enhance the language and provide features to handle the complexities in the languages that exist. Some of the major enhancements that have been put forward for the language include Generics, LINQ, Dynamics, and the async/await pattern:

In the preceding diagram, we can see how the language has evolved from its inception with managed code in C# 1.0, to async programming constructs that were introduced in C# 5.0, to modern-day C# 8. Before going further, let's look at some of the highlights of C# in its different stages of evolution.

The phrase managed code came into being after Microsoft declared the .NET framework. Any code running in a managed environment is handled by Common Language Runtime (CLR), which keeps

Generics is a concept that was introduced with C# 2.0 and allows template type definition and type parameters. Generics allow the programmer to define types with open-ended type parameters that dramatically changed the way that programmers write code. The type-safety with dynamic typed generic templates improves readability, reusability, and code performance.

The third installment of the C# language introduced Language Integrated Query (LINQ), a new construct of queries that can be run over object structures. LINQ is very new to the programming world and gives us a glimpse of functional programming on top of object-oriented general programming structure. LINQ also introduced a bunch of new interfaces in the form of the IQueryable interface, which introduced a number of libraries that can interact with the external world using LINQ. LINQ was boosted with the introduction of Lambda expressions and expression trees.

The fourth instalment also provides a completely new construct. It introduces the dynamic language structure. The dynamic programming capability helps the developer to defer the programming calls to runtime. There is a specific syntactic sugar that was introduced in the language that compiles the dynamic code on the same runtime. The version also puts forward a number of new interfaces and classes that enhance its language capabilities.

With any language, threading or asynchronous programming is a pain. When dealing with asynchrony, the programmers have to come across many complexities that reduce the readability and maintainability of the code. With the async/await feature in the C# language, programming in an asynchronous way is as simple as synchronous programming. The programming has been simplified, with all of the complexities handled by the compiler and the framework internally.

Microsoft has been working on how some parts of the source code of the compiler can be opened up to the world. Consequently, as a programmer, you are capable of querying the compiler on some of its internal work principles. C# 6.0 introduced a number of libraries that enable the developer to get an insight into the compiler, the binder, the syntax tree of the program, and so on. Although the features were developed for a long time as the Roslyn project, Microsoft have finally released it to the external world.

C# 6.0 is adorned with a lot of smaller features. Some of the features give the developers an opportunity to implement complex logic with simple code, while some of them enhance the overall capabilities of the language. Exception filters are newly introduced with this version and give a program the capability to filter out certain exception types. The exception filters, being a CLR construct, have been hidden in the language throughout its lifetime, but were finally introduced with C# 6.0.

With C# being the most dynamic language in the market, it is constantly improving. With the newer features, such as nullable reference types, async streams, ranges and indices, interface members, and many other features that came with the latest version of C#, they have enhanced the basic features and helped programmers to take advantage of these new constructs, hence making their lives easier.

Note that, during the language's evolution, the .NET framework was also made open source. You can find the source code of the .NET framework at the following link: https://referencesource.microsoft.com/.

Even though it is a decade old, the .NET framework is still well-built and makes sure to make it tiered, moduler, and hierarchical. Each tier provides specific functionalities to the user—some in terms of security and some in terms of language capabilities. The tiers produce a layer of abstraction to the end users and hide most of the complexities of the native operating system as much as possible. The .NET framework is partitioned into modules, with each of them having their own distinct responsibilities. The higher tiers request specific capabilities from the lower tiers and hence it is hierarchical.

Let's look at a diagram of the .NET architecture:

The preceding diagram depicts how the .NET framework architecture is laid out. On its lowest level, it is the operating system that interacts with the kernel APIs that are present in the operating system. The Common Language Infrastructure connects with the CLR, which provides services that monitor each code execution and managed memory, handles exceptions, and ensures that the application behaves as intended. Another important goal of the infrastructure is language inter-operability. The common language runtime is yet again abstracted with the .NET class libraries. This layer holds the binaries that the language is built on, and all of the compilers built on top of the libraries provide the same compiled code so that the CLR can understand the code and interact easily with one another.

Before going further, let's quickly look at some of the key aspects on which languages are built on the .NET framework.

The CLR provides an interfacing between the underlying unmanaged infrastructure with the managed environment. This provides all of the basic functionalities of the managed environment in the form of garbage collection, security, and interoperability. The CLR is formed with the just-in-time compiler, which compiles the assembly code that's produced with the specific compilers to the native calls. CLR is the most important portion of the .NET architecture.

As there is a layer of abstraction between the language and the framework, it is evident that each of the language literals are mapped to specific CLR types. For instance, the integer of VB.NET is the same as the int of C#, as both of them point to the same type, System.Int32. It is always preferred to use language types since the compiler takes care of the mapping of types. The CTS system is built as a hierarchy of types with System.Object at its apex. The Common Type System (CTS) is divided into two kinds, one of which is value types, which are primitives that are derived from System.ValueTypes, while anything other than that is a reference type. The value types are treated differently to the reference types. This is because while allocation of memory value types are created on a thread stack during execution, reference types are always created on the heap.

The framework class library lies in-between the language and the CLR, and therefore any type that's present in the framework is exposed to the language you code. The .NET framework is formed with a good number of classes and structures, exposing never-ending functionalities that you, as a programmer, can benefit from. The class libraries are stored in the form of binaries that can be referenced directly from your program code.

.NET languages are compiled twice. During the first form of compilation, the high-level language is converted into a Microsoft Intermediate Language (MSIL), which can be understood by the CLR, while the MSIL is again compiled during runtime when the program is executed. The JIT works inside the program runtime and periodically compiles the code that is expected to be required during execution.