Clans are of course back in Call of Duty: Ghosts. A new feature this year is that clans are now cross-platform. So you can be part of the same clan as your friends regardless of the platform. The free Call of Duty app also has deeper clan integration, like being able to create your team's clan symbol. Neat!
Those of you looking to start up your clan experience can do so starting right now. You can go create or join a clan in Ghosts, and existing clan leaders can go reserve your clan names too.