A string, in Computer science, Information theory, and Mathematics, is a Sequence of symbols, where each symbol is a member of a given set, called the alphabet. Strings often refer to finite sequences. See here.

These constructions are useful in Mathematics and Computer science.

Strings in computer science

In computer science, strings are one of the fundamental Data types used in Programming. In this case, the symbols are called characters.

However, a string can also be considered as a Data structure