It stands for "United Nations Space Command".
It is The best dam military on Earth. Kicking covenant ass since Halo CE for Xbox.
Mike: "Hey Joe, i am Joining the UNSC, i gotta help my fellow brothers fight the covenant".
Joe: "If your gunna go, then im right behind you man"
United Nations Space Command. Basically, Earth's military arm in Halo.
Foehammer: Echo 419 to any UNSC personnel! Repeat, any UNSC personnel respond!
The United Nations Space Command is the government that controls all the worlds in the Halo universe. It operates out of the United Nations. There are a few sections of the UNSC, the UNSC Marine Corps, The UNSC Navy, ONI (The Office of Naval Intelligence), and the little known UNSC Army.
The UNSC has fought several major battles in its history, starting with the Jovian Moons campaign, the Rainforest Wars, all the way to humanity's near extinction with the UNSC/Covenant War in which they emerged victoriously.
The UNSC has defeated the covenant in the war. Everyone's happy.
UNSC stands for: United Nations Space Colonies. It is used mostly in the Halo books, but you may catch some people saying it in the Halo video games.
A deranged Marine- OMFG!! THAT GRUNT JUST BLEW UP ALL THE UNSC COLONIES!!
Master Chief- Relax, you numskull. What you saw was what is going to happen to you when you finally find out that you have half a dozen needlers sticking in your side. Oh, and they were launched by a grunt too.