When you check your balance breakdown in the ‘Cashier’ section of your account overview, you will see that your total balance is made up of your ‘real’ cash balance and your ‘bonus’ or ‘promotional’ balance:
Your Cash Balance is the total amount of money you have deposited into your account, as well as any winnings you’ve made while playing with this money. You can withdraw money from your Cash Balance at any time.
Your Bonus Balance or Promotional Balance is the sum of all the available bonus funds you’ve accepted. You can play with this bonus money just like you would with your cash balance. However, the main difference between your cash balance and your bonus balance is that when you win money while playing with bonus funds, those winnings will not be made available to you until you meet the wagering requirements for that particular bonus deal.
To learn more about wager requirements, you can check out this article.