To simplify things you can say that .NET consists of three things: 1) A garbage collecting virtual machine (like the JVM) that executes Intermediary Language (

To simplify things you can say that .NET consists of three things: 1) A garbage collecting virtual machine (like the JVM) that executes Intermediary Language (IL) by just-in-time compiling it to native code. 2) A set of programming languages (C# being the most popular) that compiles to IL. 3) A broad set of libraries that are part of .NET or available from the NuGet package manager. This includes basic features like collections, JSON serialization and cryptographic primitives but also huge frameworks for web development using databases etc. In recent years Microsoft has open sourced big parts of .NET and basically rebuilt it from the ground up to make it cross platform. In the process a lot has been improved in terms of usability and efficiency making .NET a serious contender when it comes to building something like large scale cloud applications. The next major release of .NET is expected in November where the "old" Windows only version and the new improved cross platform version (.NET Core) will converge into .NET 5.