A brief explanation on Halo 3 please =]?

[ManiicPaniic&&]

I know nothing about it, and i want to know more.

 

[Eric]

The chief is back on earth the covenant(the baddies) control most of it there looking for big thing that kills on earth you must find it before them,great online multi player your an armored badass with the help of the elite races who separated from the covenant at the end of the second