Formal language

A formal language is a set of words, i.e. finite strings of letters, symbols, or tokens. The set from which these letters are taken is called the alphabet over which the language is defined. A formal language is often defined by means of a formal grammar (also called its formation rules); accordingly, words that belong to a formal language are sometimes called well-formed words (or well-formed formulas). Formal languages are studied in computer science and linguistics; the field of formal language theory studies the purely syntactical aspects of such languages (that is, their internal structural patterns).

regression testing software
pocketknife