≡

The symbol ≡ is used in mathematics with several different meanings:
* identity (mathematics), identity of two mathematical expressions
* logical biconditional (if and only if) in logic
* congruence relation in algebra

See also:
* Qián, the trigram of the I Ching that consists of three unbroken lines
* Ξ, capital letter Xi of the Greek alphabet
* , the numeral 3 in the Chinese and Japanese numerals