It is the betting “line” or gambling odds used to determine the parameters for wagering on either the favorite or underdog in a sporting event. The practice of wagering on a line was encourages. 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.
What Do the + and – Mean in Sports Betting? The – and + on a sports betting line indicates both your prospective payout and whether you’re betting on the favorite or the underdog. Negative numbers signify the favorite on the betting line. The negative number indicates how much you’d need to bet to win $100.
The novice football bettor may be a bit overwhelmed when they first create an account at an online Sportsbook and then look at the posted NFL betting lines. Most bets with your buddy will be on what NFL team will win straight up or who will cover the spread. This guide give you the basic types of Football wager types associated with a betting line.
A Total Wager is a bet on the OVER/UNDER for the Total Score at the end of the game of the combined teams. In this betting line the TOTAL is 33 (-110). For you to WIN the OVER TOTAL wager the final score would have to be 34 points combined for both teams. If the TOTAL score is exactly 33 then the wager would be graded a PUSH and your wager would be returned to you. The NFL betting line in the above example is for the full game. An NFL betting line can also be posted for 1st Quarters(1Q), 1st Half(1H) and 2ND Half(2H). Not all Sportsbooks post 1Q lines for all football games. Professional bettors are known to profit on 1H and 1Q wagers because they are able to handicap NFL games accurately because many NFL coaches script their first half plays. Moreover, 2H bets are very popular because you are able to see how well the team is playing in the first half. 
Line betting is a form of betting where the market is handicapped to make both betting outcomes equal. The bookmakers achieve this by giving both teams a margin, known as a line. If the bookmakers believe that one side is 12.5 points better than their opposition, you can back them to win by 13 or more points. Alternatively, you can back their opposition to either win the match or lose by less than 13 points. This gives you the chance to back a team at healthy odds, no matter how short or long they are on the Head to Head (H2H) market.

The example below shows the market for a game of AFL between GWS and Port Adelaide. GWS are the heavy favourites on the H2H market, paying $1.30 to win. The bookmakers have declared that in order for the odds to be even, GWS need to start 24.5 points behind their opposition, or Port Adelaide need a head start of 24.5 points.
| Team | H2H Odds | Line | Line Odds |
|---|---|---|---|
| Greater Western Sydney | $1.30 | -24.5 | $1.91 |
| Port Adelaide | $3.50 | +24.5 | $1.91 |
Working out the result of a line bet is relatively simple – just add or subtract the line from your team’s score and if their score is higher than their oppositions, it’s a winning bet.
For example, if you backed GWS at the line of -24.5, and GWS ended up winning 102-90, your bet would be unsuccessful because their adjusted total is less than Port Adelaide’s score of 90. Alternatively, if you backed GWS at the line of -24.5 and GWS ended up winning 150-90, your bet would be successful because their adjusted total is greater than Port Adelaide’s score of 90.
Line betting is available on most sports, including AFL, Basketball, NRL and Tennis.