A Steam key is a unique code that customers can activate on Steam to add a product license to their account. It is a single-use, unique, alphanumeric code that allows customers to download and play a game on the Steam platform. Steam keys are used to register a product outside of Steam, and they appear in the Steam library when you right-click the game and select Manage -> CD keys. A CD key is a printed combination of letters and numbers, found on a card, sticker, or disc included with a games packaging. It is important to note that while Steam keys are a legitimate way to purchase and play games, there are risks associated with buying keys from unauthorized resellers. These resellers are not authorized by Steam, and there is no guarantee that the keys they sell are legitimate or not stolen. Therefore, it is recommended to purchase Steam keys directly from authorized retailers or the Steam store to avoid any potential issues.