Introduction to .NET Framework
The .NET Framework is a software development platform created by Microsoft. It provides a controlled environment for developing and running applications on Windows.
.NET Architecture
The .NET architecture consists of the CLR at its core, the FCL providing reusable classes, and language compilers (C#, VB.NET, F#). Source code compiles to Intermediate Language (IL), which the CLR's JIT compiler converts to native code at runtime.
Common Language Runtime
The CLR manages code execution with memory management (garbage collection), type safety, exception handling, and security. Code under CLR is managed code. It enforces the CTS and CLS for cross-language compatibility.
Framework Class Library
The FCL is a collection of reusable types in namespaces: System, System.IO, System.Collections, System.Net, and System.Data (ADO.NET).
Assemblies
An assembly is the deployment unit in .NET — a DLL or EXE with IL code, metadata, and manifest. Assemblies can be private or shared (Global Assembly Cache). Strong naming uniquely identifies shared assemblies.
.NET Core and .NET 5+
.NET Core is cross-platform and open-source. Starting with .NET 5, Microsoft unified .NET Framework and .NET Core into a single platform called .NET.
Visual Studio IDE
Visual Studio provides IntelliSense, debugging, project templates, NuGet, and testing. VS Code is a lightweight cross-platform alternative.
Summary
The .NET Framework provides managed execution, language interoperability, automatic memory management, a rich class library, and strong tooling.