Code bowling is a competition to solve a particular problem in the most bytes possible. Must be used with other restrictions so that arbitrarily high scores aren't trivially possible.

A challenge is a challenge in which a problem must be solved using the most bytes or similar scoring criteria. Making a good challenge is difficult, since comments, no-ops and other means can be used to pad programs to an arbitrary length. Some possible ways of preventing this include banning comments or penalizing repeated characters.

In general, challenges are not popular because of this dilemma. If you choose to make one, be sure that your challenge is a good fit for and that you have taken measures to prevent arbitrary padding of programs.