Trailers have been part of the movie-going experience for almost a century, dating back to when they were shown after the feature (hence "trailers"), not before. Today, many people cite the coming attractions as one of their favorite things about going to the movies, and what's not to like? A trailer often has every single good thing about a movie, condensed into 2 1/2 minutes. That saves you a lot of time.

The scholars at IFC.com have compiled their list of the 50 greatest trailers of all time, presented in the very popular one-item-per-page format that all Internet users love. Great trailers aren't necessarily for great movies. In fact, a lot of these selections are for bad movies. It's the trailers that are good. And what constitutes "good"? IFC says, "Ultimately, we decided that the best trailers are those that most effectively combine art and commerce, and that sell and entertain with equal skill." Amen to that.

I'll be a spoiler and tell you their choices for the top five: Jerry Seinfeld's Comedian at #5, Miracle on 34th Street at #4, followed by Cloverfield, Psycho, and, in the top spot -- the best trailer of all time -- Alien. What do we make of the fact that the top three (in IFC's estimation) are for thrillers? And what did they leave off the list?

We've got the Alien trailer from YouTube after the jump, where no one can hear you scream.