Oooh, I've been waiting for someone to ask me to explain what Rooster Teeth is for a while now (idk why people stylize it as one word, if you look at their logo or how they spell it on their site and everything it's clearly two words).  Because I'd say 85-90% of my followers aren't fans.

I can't explain what they are in just a few words because they do so many things.  But maybe their slogan "Comedy. Gaming. Community." works.  Rooster Teeth is a small production company in Austin, Texas that got its start by creating a machinima comedy webseries called Red vs. Blue based off of the Halo games.  Over the years they've grown to produce a lot more content that's all available for free on their website or on youtube (some content is only available if you're a paid sponsor, but hey, they gotta pay the bills).  This includes but is not limited to doing weekly video podcasts, hilarious live-action short films, an anime inspired webseries called RWBY (that I still need to watch), the wildly popular Rage Quit, and (what is probably the most popular group of RT employees) Achievement Hunter.  AH started up to be a branch of the company dedicated to helping Xbox gamers to unlock all the achievements in certain games.  Then one day they discovered upon a format called "let's plays", where people play through games and provide their own commentary.  Now Achievement Hunter has their own channel aptly titled LetsPlay dedicated to these kinds of videos.  And ugh, the amount of stuff AH puts out is crazy insane too.  I've been a fan for two months and I still haven't seen everything I need to see.