The first thing that strikes you when learning chess opening theory is volume.
Modern theory is so broad that variations increase exponentially with the number of moves. You can get a sense of this by reading any opening book and trying to memorize as many lines as possible.
But there's something unsatisfying about a textual representation of chess variations. There's no sense of magnitude until you poke around for a few minutes—and even then, you don't comprehend what you haven't seen.
So, here are tree-based representations of two popular chess openings: the Queen's Gambit and the Sicilian Defense. Queen's Gambit because it's my opening of choice, and Sicilian because it's notoriously theoretical.
The Sicilian, as expected, is ludicrously complex, but it looks like my Queen's Gambit didn't disappoint. I'll take that as an ego boost.