An operating system (OS) is the program that, after being initially loaded into the computer by a boot program, manages all of the other application programs in a computer. The application programs make use of the operating system by making requests for services through a defined application program interface (API).

(computing) operating system.

Play the CALL OF DUTY you know and love on the go on your mobile device. With multiplayer modes such as Team Deathmatch, Domination, and Kill-Confirmed on iconic maps such as Shipment, Raid, and Standoff, CALL OF DUTY: MOBILE has it all!

Choose Advanced mode: There are two methods of control, simple or advanced that you'll be presented at the start of the game. Simple is autofire when you're pointing at someone, but Advanced gives you full control and it's the latter you should choose - even if it means getting a little more practise.