Editing Parity bit (section)

==Parity==
In mathematics ''[[parity (mathematics)|parity]]'' can refer to the evenness or oddness of an integer, which, when written in its [[binary numeral system|binary form]], can be determined just by examining only its [[least significant bit]]. 

In information technology parity refers to the evenness or oddness, given any set of binary digits, of the number of those bits with value one. Because parity is determined by the state of every one of the bits, this property of parity—being dependent upon all the bits and changing its value from even to odd parity if any one bit changes—allows for its use in error detection and correction schemes.

In telecommunications the parity referred to by some protocols is for error-''detection''. The transmission medium is preset, at both end points, to agree on either odd parity or even parity. For each string of bits ready to transmit (data packet) the sender calculates its parity bit, zero or one, to make it conform to the agreed parity, even or odd. The receiver of that packet first checks that the parity of the packet as a whole is in accordance with the preset agreement, then, if there was a parity error in that packet, requests a retransmission of that packet.

In computer science the parity stripe or parity disk in a [[RAID]] provides [[Error detection and correction#Parity bits|error-''correction'']]. Parity bits are written at the rate of one parity bit per ''n'' bits, where ''n'' is the number of disks in the array. When a read error occurs, each bit in the error region is recalculated from its set of ''n'' bits. In this way, using one parity bit creates "redundancy" for a region from the size of one bit to the size of one disk. See {{section link||RAID array}} below.

In electronics, transcoding data with parity can be very efficient, as [[XOR#More that two inputs|XOR]] gates output what is equivalent to a check bit that creates an even parity, and XOR logic design easily scales to any number of inputs. XOR and AND structures comprise the bulk of most integrated circuitry.