Odds-on & Odds-against Explained

In betting, a selection which is Odds-on requires that you stake an amount which is more than the amount that you expect to make in profit.

Event favourites are odds-on, as their selection yields less profit than the amount staked to back them, hence the term "odds-on favourite".

The opposite of this concept - Odds-against, means that the amount you win is greater than the amount you stake.