The number-one key to success here (as it is with any type of sports bet) is understanding what value is and knowing when and how to take advantage of it. Value, in a nutshell, is finding sports bets that are paying you at a better rate than you think they should. If you place enough of these bets to overcome variance, you’re going to be a long-term winner.
Identify the favorite. Lines with a - before the number (i.e. -200) indicate the favorite. A -200 should be read as: "For every $200 wagered, I win $100." When there is a negative sign, the line should always be read with relation to 100. That does not mean you have to bet that much, it's just easiest to understand! When a + sign is present, just reverse the reading, always keeping reference to 100:
This used to be impossible or extremely time-consuming when only land based sportsbooks and casinos existed. You would have to drive hundreds of miles if you wanted to get to another casino and then hope they still had the different line. This would cost you travel money as well as time. Online sportsbooks make this extremely easy now. You can check several sportsbooks lines on a game within a matter of seconds or minutes. It doesn't cost you any additional money, just a few minutes of your time and can have a huge impact on the outcome of your bets.
Sports betting has been around since 1000 B.C in China, where betting on animal fights was commonplace. In ancient Rome, one could wager on the Gladiatorial games. The idea of betting on sports is as old as organized sport itself. But up until the 1940s, bettors were fairly limited in what kind of bets they could make. The standard system of odds would allow bets on, for example, the 3-1 odds that the Steelers would beat the Browns.