In order to prevent a break-even scenario, many handicappers will add a half-point to point spreads. For example, the New York Knicks may be favored by 3.5 or 3 and a hook.
The half point is known as a hook because it draws the bettor to one side of the line or the other. If you do not want the hook, that means you are taking the under. If you take the hook, that means you are taking the points and taking the over. You will almost never see a point spread for any professional sport without a hook, that is how much bookmakers and casinos want to avoid a break-even scenario. Since a half-point cannot be scored in any game, adding a hook ensures that one side of the bet will win and one side will lose. This benefits the sportsbooks because they design the betting lines to attract an equal amount of bets to both sides of the line.