What is the difference between string and string builder?

In this article I will explain the  difference between string and stringbuilder in c#.

String

String is immutable object  (i.e.  once created cannot be changed ) and It always create new object of string type in memory.  If we want to append or replace something in string then it will discard the old value and will create new instance in memory to hold the new value. String belongs to “System” namespace.

 Example

 string   str = "Hello Visitor";

 // create a new string instance instead of changing the old one

 str += "How Are";

 str += "You ??";

 Stringbuilder

 StringBuilder is mutable, means if create string builder object then you can make modification in the data i.e. you can append and replace the string  without creating new instance for every time.it will update string at one place in memory doesn’t create new space in memory. Stringbuilder belongs to “System.Text”  namespace.

Example:

StringBuilder strbuilder = new StringBuilder("");

strbuilder.Append("Hello");

strbuilder.Append("Visitor ");

string str = sb.ToString();

Please mention in the comments in case you have any doubts related to the post: difference between string and stringbuilder.