As we have seen in our lesson about the fork any piece can create a fork, even a pawn or a King. However the most common fork is the Knight fork. The way the Knight moves makes it more likely that the threat is overlooked.
I have created some knight fork exercises, but before trying to solve these it may be a good idea to re-read the lessons mentioned above.

You can drag and drop a piece to make your move.
If you like some more exercises you may also be interested in the mate in one or mate in two problems.