Point spreads are used in football and basketball. The point spread (or 'line') will try to make the game an even game by adding points to the score of the underdog or subtracting points from the favorite.
A game has four (4) straight wagering situations. You can wager on the 'side' of the game or the 'total' of the game. When wagering on a 'side', you can choose to wager on (a) the favorite team (the team most likely to win the game, or has the odds in its favor) or you can choose (b) the underdog (the team most likely to lose the game, or has the odds against it). A 'total' (or over/under) is the combined amount of points both teams will score in a game. When wagering on a 'total' (or over/under), you can choose to wager on (c) 'over' or (d) 'under' the total points scored.