GP, or Game Points, are a feature in Call of Duty Online that acts as currency which is used to buy weapons, attachments, perks, player character customizations and camouflages.
Ranking up allows weapons and equipment to be unlocked, as with other Call of Duty games, but they must be purchased with GP or CP to be used.
GP gaining is simple: excluding challenges the player will receive 10% of their experience gained in public matches in GP. For example, if a player got 3000 experience points in one game, the player would earn 300 GP.
This type of currency is free to acquire inside the game and no real money is required.