If you study the way the knight moves, you will see that if the

knight is any where but near the center of the board it is less effective.

If its on the EDGE of the board (files A or H or ranks 1 or 8 ) it is called "half a knight" , because it can onlt move 4 of it's 8 possable squares.

If it is in a corner (A1,H1,A8,H8)it has only 2 squares to move.

A PLACE TO BE AVOIDED.