Type String

Along with type Number, this is probably the most commonly used type of all.

Data of type String contains what might be thought of as a label in the non-technical world. 

You could use a variable of type String to store your name or your telephone number.

Your telephone number

If you store a telephone number as type String, you cannot perform arithmetic using that data.

This is true even if it consists solely of the digits from 0 through 9 inclusive.

You can only perform arithmetic using data of type Number.