Get your haxx here. No piracy.
Don't worry, some homebrew are similar to roms, great gameplay yo. Like this game.
What is fun without roms?
Homebrew is what we call unofficial software made by amateur developers for closed systems such as the 3DS. This includes both games and applications, and in practice getting homebrew on your 3DS means you'll be able to:
Make your own badges to use in home menu.
Play out-of-region games you own.
Make your own themes to use in home menu.
Play old SNES games with blargSNES. (sux)