Parity Bit

• A parity bit is a single bit added to a binary data transmission used to indicate if whether the 0's and 1's within that data transmission is an even or odd number.
  

• It is useful in detecting errors.                            
• But it does have several drawbacks. One of them is that it cannot correct the errors, just shows if they exist.
  
  

 8-bit binary number with the ninth digit being the parity bit

• If you convert data into binary stream and count the number of '1' in the data, it would be only one of two cases.. the total count of '1' is Even or Odd. 

• In Parity Check method, transmitter reorganize the original data so that the total number of '1' is only Even (Even Parity) or only Odd (Odd Parity).