You earn a commission when you sell a product or service. This commission is a percentage of the sale price. Companies often use this method to motivate salespeople. You can find commissions in many industries. Real estate agents earn commissions on property sales. Affiliate marketers earn commissions by promoting products online.You receive your commission after the sale is complete. The amount varies based on the agreement with the company. Some companies pay a flat fee while others pay a percentage. You should understand the terms before starting.