CS cases are special containers in the game CS:GO that contain various items such as weapon skins, gloves, stickers, and other visual enhancements. These cases can be obtained in-game by completing matches or purchased on the Steam marketplace. Each case has its own unique collection of items, and the chance to receive a rare or valuable item depends on its rarity and value. Players can open cases using special keys, which can also be purchased in-game or on the marketplace.