You are able to find cards laying around or you can purchase them at a shop.

Each card is an ability that can be used ONLY ONCE after use the card will be ripped up. Some cards work with you like giving you, Ammo, Scrap, ability to see enemies through walls for a short time, etc. Other cards will pretend to work with you however they could give you, blindness, less sanity, less stamina, etc.