Counter-Strike 1.1 , the "CD Key" is a unique alphanumeric code used as a digital fingerprint to authenticate your copy of the game and verify it was purchased from an authorized distributor Primary Purpose Authentication
: In the early days of online gaming, the CD key was used by the WON (World Opponent Network) to authorize players for multiplayer matches. If a key was already in use by another player, you would be unable to join online servers. Steam Account Ownership : When Valve transitioned from WON to the Steam platform cd key cs 1.1