Tropes are storytelling devices and conventions that a writer can reasonably rely on as being present in the audience members’ minds and expectations.
The site’s name is misleading… while there are plenty of TV tropes, you’ll also find examples from journalism, comics, video games, etc. From the “air vent escape” to “loser archetypes” to the “hard work montage,” this is loads of fun.
Oh, and it’s a wiki! (Via.)