Promo codes can offer a variety of benefits depending on the promotion. Common types include percentage discounts (like 20% off), fixed amount discounts (e.g., $10 off), free shipping, buy-one-get-one deals, or bonus gifts with purchase. Some are only valid on certain products or categories, while others may require a minimum purchase. Brands use different types of codes to target new customers, reward loyal shoppers, or boost sales during special events or holidays.