Introduction to the differences between String and string in c

I don't know if you noticed that in c# string you can write string and String, so what's the difference?

string is a class in c#;

String is the class of Framework;

C# string maps to String of Framework.

If you use string, the compiler will compile it to String, so if you just use String you will save the compiler a little bit of work.

That is to say,

string is just another name for String