What's the premise of "Halo"?

Search: halo

Why: We were just watching some commercial, and some guy on it looked like Iron Man, and I said, "Is that a Power Ranger?" and Chandler said, "That's Halo," and I asked if Halo was a person?, because I guess I always thought of it ("Halo") as some sort of place or universe or something, and he said he didn't really know... I think that brings us up to speed.

Answer: This is as much as I'm willing to read at this hour. You guys, I was woken up at 7:30 CST this morning because Sadie was catching a lizard, and then I went on 2 airplanes and to 3 airports, and now it's 12:30 PST...

In the past, an intelligent race called The Forerunners used their advanced technology to protect life, but were caught off-guard by an alien parasite known as the Flood. The Flood, which spread through infestation of sentient life, threatened and overran many worlds in the galaxy before the Forerunners could attempt to contain the threat. A group of Forerunners conceived a final solution—using an installation known as the Ark, they built seven large ring-shaped megastructures known as Halos. The Halo Array, when activated, would destroy all sentient life in the galaxy—depriving the Flood of their food. Delaying as long as they could, the Forerunners finally activated the rings and disappeared.

Here's the "Halo Array," I think:

Source: Wikipedia

The More You Know: Speaking of getting up at dawn, here is Ben's new favorite song. Get it out of your head!