Well-formed formula
![This diagram shows the syntactic entities which may be constructed from formal languages. The symbols and strings of symbols may be broadly divided into nonsense and well-formed formulas. A formal language can be thought of as identical to the set of its well-formed formulas. The set of well-formed formulas may be broadly divided into theorems and non-theorems.](/Images/godic/202501/24/Formal_languages.svg3621.png")
In mathematical logic, a well-formed formula, shortly wff, often simply formula, is a word (i.e. a finite sequence of symbols from a given alphabet) that is part of a formal language. A formal language can be considered to be identical to the set containing all and only its formulas.