what is string

Answer 1

You can look at it as on tab of characters with some nice additional methods.

Answer 2

it is a data type which used for a set of characters...
for example: when you wanna work with numbers you use int (a data type) but when you are about to input and output a set of characters(EX: "hello world") you should use string ...
note that we have char(a data type) which we have to put in single quotation but strings usually are in double quotations..

hope to be useful