Parity is a concept of equality of status or functional equivalence. It has several different specific definitions.

• parity (physics): In physics, particles have a quantum mechanical property of parity.
• parity (mathematics): In mathematics, parity indicates whether a number contains an even or odd number of bits. If a number contains an even number of bits, it is said to have even parity, otherwise it has odd parity. In a computer memory, the parity of a number is often stored as an extra bit to verify the reliability of the memory.
• parity (telecommunication): In this usage, the number of '1' bits in the binary value is counted. Parity is even if there are an even number of '1' bits, and odd otherwise.
• In medicine, parity is defined as the number of pregnancies that a woman delivers past 24 weeks. A grandmultiparous woman is a woman who has delivered four or more infants who have achieved a gestational age of 24 weeks or more.