im sorry, i know you didn't know, but its just really funny to me.
as brawny pointed out, just check out the wiki, but ill explain a little here:
the Prime series is the first to go 3-D on Samus's sweet ass, and it has a lot to do with the new substance called Phazon and Samus's rival Dark Samus (not much is known about her/it).
in this game, you can let Samus get corrupted by the phazon to get a lot more power, speed, etc at the cost of a full energy tank (health).
the story is something like this: The Space Pirates (evil group) have created a virus that leaves the Galactic Federation (good guys) exposed. they have hired Samus and other bounty hunters to deliver antidotes. and along the way you run into the Space Pirates and probably Dark Samus and all hell breaks loose.
basically.