A wager requirement is a restriction that an online casino puts on their bonuses that states a player must play a certain amount of bets/ hands before they are able to cashout the bonus. The amount that must be wagered is usually between 8 - 80 times the initial deposit plus the bonus.
Here's an example of a wager requirement:
Ladbrokes Casino requires you to wager the bonus 8x's only. So if you deposit $100, you get $100 free. Now you have $200 but only $100 has a wager requirement associated with it. So take the 8x's wr X $100 (bonus) and that gives you $800 in wager requirements. Doubles, splits and surrenders all count towards the wager requirement.
Now take the $800 and divide it by $5, you only have to play 160 hands to clear the bonus.
Now you see how easy it is to clear these bonuses.
Sit back and have some fun at the casinos expense!