In object-oriented, an immutable object is an object whose state cannot be modified after it is created. This is in contrast to a mutable object, which can be modified after it is created. From the StringBuilder Class documentation: The String object is immutable.

Mutable : We can assign multiple values to mutable string and object state can be altered. Best example of Mutable is stringbuilder object can be used. We can multiple concatenation to mutable string. Mutable have very good flexibility to change object state, mutable string can generate long string. We can use given below namespace to use mutable string in c# using System.Text; //* namespace used to import string builder StringBuilder strLong = null; //* [Mutable String] example strLong.Append("Technology"); strLong.Append("Cloud");

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Mutable means "can change".Mutable type, in C#, is a type of object whose data members, such as properties, data and fields, can be modified after its creation.Stringbuilder is example of this