Flag

In Capture the Flag Multiplayer gametypes, the Flag is what must be taken, ran back to your base, and "captured." Halo's CTF is much like the real-life game, except that you actually have a real flag on a flag pole, which is usually unheard of in the real world. Also, rather than hiding the flag, it is always in a pre-determind position, often in the middle of the base, and your only method of defending it is to kill other people and wait for them to respawn.

Red Flag


The red flag is a white cobra on top of a black diamond.

Blue Flag


The blue flag is a blue hawk on top of two crossed blades

Trivia
On Bungie.net, the description of the flag states that "It's right next to the headlight fluid." This is an obvious reference to Red vs Blue, in which Donut is tasked with finding elbow grease and headlight fluid and inadvertantly captures the Blue flag.