Answer by user3296 for What is the difference between String and string in C#?

There is one difference - you can't use String without using System; beforehand.

Updated:

"String" with a capital "S" is a keyword that refers to the built-in string data type in the .NET Framework's Base Class Library. It is a reference type that represents a sequence of characters.

On the other hand, "string" with a lowercase "s" is an alias for the "System.String" type, which means they are essentially the same thing. The use of "string" is just a shorthand way of referring to the "System.String" type, and it is used more commonly in C# code.

Both "String" and "string" are interchangeable in C#, and you can use either one to declare a variable of type string.

String myString = "Hello World"; // using the String keywordstring myString = "Hello World"; // using the string alias

However, it is recommended to use the "string" alias in C# code for consistency with the rest of the language's syntax and convention.

Here you can read more about C# String