In C# (and .NET) a string is represented by class System.String. The string
keyword is an alias for this class.
The System.String class is immutable, i.e once created its state cannot be altered.
So all the operations you perform on a string like Substring, Remove, Replace, concatenation using +
operator etc will create a new string and return it.
See the following program for demonstration -
string str = "mystring";
string newString = str.Substring(3);
Console.WriteLine(newString);
Console.WriteLine(str);
This will print string
and mystring
respectively.