Takoyaki is a compound word in Japanese. Tako = octopus, Yaki = grilled, fried, etc. So takoyaki is basically fried balls of dough and octopus. I've actually always been a bit curious as to how they are able to make it into such a nice, spherical form, and now I know.
It all begins with a cast-iron pan that has many dimples in it. You pour in an egg-water-flour-fishy mixture into each of the dimples, and then put in green onions and small chunks of octopus. After just enough time has passed, you then take a little skewer (basically a large toothpick) and finagle around the now semi-cooked spheres so that the uncooked side is down. Repeat the process until everything is cooked evenly, then enjoy with a bit of sauce and fish flakes. This was the first time I've learned how to make any sort of Japanese food, so it was pretty exciting (and actually pretty tasty to boot). I'm sure my description wasn't that helpful, so here's a picture of my host sister manning the takoyaki production line.