Also known as a Goal Line. This type of wager is similar to spread betting, but with a fixed stake. The bookies will choose a particular goal value, and give you the opportunity to predict whether there will be more, or less goals scored than this figure during the match.
For example, if the bookmakers think that a particular football match will be high scoring, you may be quoted odds of 5/4 for a total of less than 2.5 goals, and 5/6 for more than 2.5.