Glossary? More of an acronym list.

FPS: First person shooter.

COD : Call of Duty. The first title in the franchise was released in 2003 and when discussed generally includes the newer Modern Warfare titles. COD competes with BF3 in the ” realistic infantry combat with ironsights” FPS niche and is often looked down on as the more popular but less “skillful” game by the Battlefield 3 community.