The two main sports that use point spreads are football and basketball. Since the two teams playing each other are rarely even matched, the point spread comes into play. The point spread helps balance the chances of a team winning through the adjustment of the final score with the point spread.
A typical point spread reads: Team A-7 vs. Team B. The favorite team who is expected to win must give points to the winner team, Team B. The number of points is usually based on the points they are favored by, in this case seven. Therefore, Team A must not only win the game but with an additional seven points above Team B in order for someone betting on Team A to win. Someone betting on Team B wins if Team B wins or they lose the game by less than seven points. If Team A wins by exactly seven points, then there is a push and a refund is issued to anyone who bet on either team.
Sometimes point spreads can be reversed to read from the underdog's perspectives. Using the above example the point spread could also read: Team B +7 vs. Team A. Just because the point spread has changed does not mean the betting action has changed. Team A must still win by seven.
If you prefer to do things mathematically, you can subtract the point spread number from the favorite teams score at the end of the came and then compare it to the underdogs score. Alternately, you can add the point spread score to the underdog's score at the end of the came and compare the points.
By understanding point spreads, it can make betting easier. When you can understand the way betting is connected it will help you enjoy your time better.