When thinking about placing a bet, it is vital that you know how the product you are playing works. If you do not, then do not place a bet.
The main risk when gambling is losing money, so knowing what you are betting on means that you can make informed decisions about the money you are spending when gambling.
Sports
Betting on sports involves predicting the outcome of (normally) a sporting event. This could either be the final result or any event that occurs within the game. The odds (or price) that you take are set by the company and represents their idea of an event occurring.
To win, your selection needs to be correct. Although, there is no such thing as a guaranteed winner. Even when backing a favorite, winning is never guaranteed as sports ultimately are just too unpredictable.
Unlikely outcomes are not just possible, they happen quite regularly.
So how do "odds" work?
The odds are a representation of how likely the bookmaker thinks it is that something will happen. The lower the odds, the more likely it is to occur and therefore the lower the winnings if you are successful.
Odds can be displayed as either American, decimals, or fractions, they all equate to the same chance of winning, they are just displayed differently.
For example, +200 is the same as 2/1 and 3.00. If you placed $1 on these odds and you were to win, you would get a total of $3 back; your original $1 wager and your winnings of $2.
Some more examples:
$1 @ +150 (6/4, 2.5) would return $2.50 in total if you won. That is your $1 wager and your winnings of $1.50.
$1 @ -150 (4/6, 1.66) would return $1.66 in total if you won. That is your $1 wager and your winnings of $0.66.
$1 @ +1000 (10/1, 11.00) would return $11 in total if you won. That is your $1 wager and your winnings of $10.
But remember chance and unpredictability play a part so the outcome that people are expecting doesn't always happen, the favorite might get beat, the outsider that no one thought could win might just have its day in the sun. So never wager more than you can afford to lose, gamble responsibly and within your means.