Tvtropes.org is a website dedicated to cataloging every trope in existence. It also has pages on most every TV show, film, video game, cartoon, and every other piece of media known to man. Its other purpose is to ruin your life.
Tropes are hard to define. However, you know them when you see them. For instance, the trope "Only Sane Man" (tvtropes.org/pmwiki/pmwiki.php/Main/OnlySaneMan) refers to a situation you have probably seen before; something completely insane is going on and only one person notices.
See that guy in the back on the right? Yeah, that's him.
Tropes make up the meat and potatoes of tvtropes. Without them, it would be a cheap wikipedia knock-off.
Each trope page contains a list of examples. This is where you will spend most of your time, looking at the various examples and feeding your soul to the gods of the internet.
Here's one of them now. He hungers.