Promo codes are used frequently to provide discounts or special deals to customers in a variety of sectors, including retail, food and beverage, and travel. In order to use the discount or offer, promo codes must usually be entered during checkout or when making a reservation. Use of promotional coupons should be done with caution, though, as some may be invalid or no longer valid for some goods or services. To make sure you're receiving the best deal possible when using a promo code, it's best to carefully read the terms and conditions first.