Create an Operator is the revamped character customization system for Call of Duty: Advanced Warfare, allowing a new level of freedom to precisely fine-tune your operator exactly the way you want.
There are two main ways to earn and unlock new gear: earn it by completing challenges, or find it in Supply Drops. Similar to weapons, each piece of gear has a rarity of Enlisted (common), Professional (uncommon), and Elite (rare). Completing various challenges throughout Campaign and Multiplayer will also unlock themed gear associated with those challenges.
Any new gear you earn through the Supply Drop system goes into your gear storage, and you can freely swap around gear to customize your character as you see fit.