I'll be honest, Halo's story confuses the hell out of me. Not the general outline, I get that, but the specifics and history of the universe are presented as a mess for someone who just plays the games and doesn't get knee-deep in the external fiction.
Why am I here? Who's that guy? When did that happen, and what the hell did that thing just say? That sort of thing.
So I'm appreciating this simple guide, laid out in chronological form, to the overall backstory of the universe, provided by GameFront. Though even after reading it through a couple of times, boy, they could have trimmed some corners there, made it a little neater.
UPDATE - Well, as you'll see if you scroll down to the comments, seems there are a few errors with this. Given my thoughts on the canon's complexity, I sympathise, but it's still something to be aware of! You can find around 3 million corrections below.
UPDATE 2 - New timeline posted with corrections made!
Halo Story Timeline [GameFront]