In C# a string is immutable(unchangable) but we have insert()method which insert's a string in between..expln

in c# a string is unchangable if it is created with String class..but in the same class we have a method called string() method which inserts a string in preexisting string...means we are going to change a string it is working properly...so, why we are saying that a string created with a string class is unchangable?

In C# a string is immutable(unchangable) but we have insert()method which insert's a string in between..expln
that's true u can't change a string created with the String class, but the insert() method use the old string and the new string that u want to insert and create a new string, not the old one