What is "substring"

n. (context computing English) A (possibly zero-length) string of characters that is contained in another string.

A substring of a string S is another string Sʹ that occurs "in" S. For example, "the best of" is a substring of "It was the best of times". This is not to be confused with subsequence, which is a generalization of substring. For example, "Itwastimes" is a subsequence of "It was the best of times", but not a substring.

Prefix and suffix are special cases of substring. A prefix of a string S is a substring of S that occurs at the beginning of S. A suffix of a string S is a substring that occurs at the end of S.