1. What is .NET?
.NET is a development platform, or developer platform. Using .NET you can create different types of applications, using a variety of development languages, editors and tool libraries to create web, mobile, desktop and game applications. Its core features are: free, open source and cross-platform.
2. Language & platform concept distinction
Let's first understand what is the .NET development platform:
Simply put, the development platform is a working platform provided for application software development. The .NET development platform mainly includes common language runtime (CLR) and framework class library (FCL). Among them, FCL includes the basic class library (BCL) and framework class libraries such as ASP.NET (Core), ADO.NET, WPF, and WinForm.
It is often heard that .NET corresponds to Java. Strictly speaking, it is wrong. Java corresponds to C#, JVM corresponds to CLR, and JDK corresponds to .NET Framework/.NET Core/.NET 5+ SDK. There are multiple languages on the JVM and multiple languages on the CLR. For example, there are Java, Scala, JPython, etc. on the JVM, and C#, F#, IronPython, etc. on the CLR. Of course, usually we don't have to deliberately distinguish the corresponding relationship. When we hear someone compare .NET to Java, it doesn't have to be true at all. Because the C# language occupies an absolutely dominant position in the .NET platform market, people have tied .NET and C# together by default. For example, people are used to talking about .NET ecology and Java ecology, but rarely hear about C# ecology. Others equate .NET with .NET Framework or .NET Core. It is also wrong to be precise. .NET is a development platform. .NET Framework is a development framework implemented on the .NET platform for Windows systems. .NET Core/.NET 5+ is implemented on the .NET platform to support multiple operations. A cross-platform development framework for the system.