It's not a Microsoft thing, and you don't need to analyze and manipulate bits or anything like that - it's just one of the lesser-known features of the XOR function. XOR essentially forms a triangle with two things, such that:

If C = A XOR B, then B = A XOR C and A = B XOR C.

Therefore, you can switch two values by just cycling around the circle...

So...

Position 1 Position 2 Result of XOR

A B C (now put this in Position 1)

C B A (now put this in Position 2)

C A B (now put this in Position 1)

B A

So we've done a nice swap. You don't need to try to complicate matters by understanding WHY xor does this.