What is line betting? Line betting is a form of sports betting whereby the bookmaker handicaps a team by setting a margin, which effectively makes the game equal. This margin is referred to as the line, hence where the term line betting originates. Line Betting is only available for events where there are two possible outcomes. For example, if the bookmaker believes Team A is a 10 point better team than Team B, the bookmaker can handicap Team A 10 points.