Generally, promo codes are “promotional offers” which means customers will usually have to purchase something and in return they will receive something for free or get a discounted rate. They are often geared towards a certain purchase type such as requiring you to spend a certain amount of money or buying a certain product or service.
If you complete the qualifiers, then you can usually redeem a code online to get your discount or free product or service. Some offers do not require qualifiers as those particular companies want bring in new business any way they can. They basically just want you to spend your money with them on anything and they will provide you with a discount. Companies like Lyft are offering these types of promo codes. I found some great ones at https://www.ondemandly.com/lyft-promo-code/ that are worth trying for anyone thinking of trying out ride sharing services.