In this way, using one parity bit creates 'redunancy' for a region from the size of one bit to the size of one disk. When a read error occurs, each bit in the error region is recalculated from its set of n bits. Parity bits are written at the rate of one parity bit per n bits, where n is the number of disks in the array. In computer science the parity stripe or parity disk in a RAID array provides error- correction. 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 re-transmission of that packet. For each string of bits ready to transmit (data packet) the sender calculates its parity bit, zero or a one, to make it conform to the agreed parity, even or odd. The transmission medium is preset, at both end points, to agree on either odd parity or even parity. In telecommunications the parity referred to by some protocols is for error- detection. 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 information technology parity refers to the evenness or oddness, given any set of binary digits, of the number of those bits with value one. In mathematics parity can refer to the evenness or oddness of an integer, which, when written in its binary form, can be determined just by examining only its least significant bit. If its actual bit value is irrelevant to its function, the bit amounts to a don't-care term. The function of such bits varies with the system design, but examples of functions for such bits include timing management or identification of a packet as being of data or address significance. In such cases where the value of the bit is constant, it may be called a stick parity bit even though its function has nothing to do with parity. If a bit is present at a point otherwise dedicated to a parity bit but is not used for parity, it may be referred to as a mark parity bit if the parity bit is always 1, or a space parity bit if the bit is always 0. Even parity is a special case of a cyclic redundancy check (CRC), where the 1-bit CRC is generated by the polynomial x+1. If the count of bits with a value of 1 is odd, the count is already odd so the parity bit's value is 0. For a given set of bits, if the count of bits with a value of 1 is even, the parity bit value is set to 1 making the total count of 1s in the whole set (including the parity bit) an odd number. In the case of odd parity, the coding is reversed. If the count of 1s in a given set of bits is already even, the parity bit's value is 0. If that count is odd, the parity bit value is set to 1, making the total count of occurrences of 1s in the whole set (including the parity bit) an even number. In the case of even parity, for a given set of bits, the occurrences of bits whose value is 1 are counted. Accordingly, there are two variants of parity bits: even parity bit and odd parity bit. The parity bit ensures that the total number of 1-bits in the string is even or odd. Parity bits are generally applied to the smallest units of a communication protocol, typically 8-bit octets (bytes), although they can also be applied separately to an entire message string of bits. Parity bits are a simple form of error detecting code. JSTOR ( January 2013) ( Learn how and when to remove this template message)ДЄ parity bit, or check bit, is a bit added to a string of binary code.Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.

Odd parity