Difference Between String And StringBuilder Using in Asp.Net C#

Difference Between String And StringBuilder 

S.No	String	StringBuilder
1	It is Immutable.	It is Mutable.
2	String Using System NameSpaces.	StringBuilder Using System.Text Namespaces.
3	Once Create String Object We Cannot Modify.	Once  Create String Builder Object We Can Perform Any Operation . e.g Insert,Replace,Append.
4	String Cannot  Append Keyword.	StringBuilder  Can  Append Keyword.
5	String is Slower Than StringBuilder Because Create New Instance for Every Time. e.g          string a = "1";         string b = "2";         string c =a+b;	StringBuilder is Faster Than String Because Create One Instance for Every Time e.g  StringBuilder S= new StringBuilder(""); S.Append(""); S.Append("test "); string c = S.ToString();