A bonus is a financial compensation that is above and beyond the normal payment expectations of its recipient. Bonuses may be awarded by a company as an incentive or to reward good performance. Typical incentive bonuses a company can give employees include signing, referral, and retention bonuses.
An annual bonus is usually based on overall company performance. This means you may get a large or small bonus (or no bonus at all) depending on how successful your organization or specific department was that year, as well as how big a part of that success you were. This can also be considered profit sharing.