Football point spreads refers to the difference in score between two opposing teams as quoted by a sports book.
For example) In football, a typical point spread might read as one team favored by six points. In this scenario the favorite must win the game by more than six points for anyone gambling on that club to win their bet. Conversely, the underdog must lose by less than six (or win) for their backers to collect.
In terms of NFL point spreads, one might favor a team by four points. In this situation, the favorite must win the game by more than four points for anyone gambling within the pool to win their bet. An underdog must lose by less than four points for their bookie to collect. A point spread is efficient for betters because an underdog team gets points, while the favorite would give points.