The Alien series is an irrefutable juggernaut, with the original movie being just the tip of the, uh, jugger. It's such a cultural touchstone that it's almost irresponsible not to have at least some working knowledge about the franchise. But we get it, you're busy.
To bring you up to speed, we've assembled a Matrix-style download that you can pour directly into your brain to become an instant expert.
Source: Vocal Media
Source: Alien Anthology Wiki
Source: Digital Spy
Source: Keegan, Rebecca. The Futurist: The Life And Films Of James Cameron. Three Rivers Press, 2010.