Toro is the meat the comes from the belly area of a tuna. It is one of the most delicious things I've ever eaten. Toro would definitely be on the list of things I would want to continue to eat if I could only choose a couple of things.
Toro is fattier than other parts of the tuna. It's not fatty in the same sense that a piece of beef might be fatty. Instead, the fattiness gives Toro an almost buttery flavor.
Toro is also generally one of the more expensive cuts of fish. You can see here
that some of these toro sushis are as much as $16 just for 2 pieces.
The price basically reflects where the toro is from. The fattier part is the
most expensive. You can see here where the different parts come from. Types 1,
2 are called oh−toro which I believe is the best. Type 3 is called
chu−toro which is the middle. I'm not sure what type 4 is but as it
doesn't look as fatty I'm assuming it's not as yummy.