title: What is an XOR sum?
body: <p>I am not sure of the precise definition of this term. </p>
  
  <p>I know that a bitwise XOR operation is going bit by bit and taking the XOR of corresponding bits position wise. Is this result termed the 'XOR sum'? If not, what is an XOR sum, and how do you use XOR to implement this addition?</p>