The mouths of most mammals can perceive five basic tastes: sweet, salty, sour, bitter, and umami (the "delicious" taste added by MSG and many amino acids). Most animals, including humans, find sweet, salty, and umami to be attractive tastes. (Cats are an exception: They are genetically unable to taste sweet.) Much of what we think of as "taste" is really odor, detected in the back of the nose as we chew and swallow. A quality called "mouth feel" by food experts also plays a role in our attraction to particular foods. We seem to especially like the richness of foods that contain microscopic spherical particles, like fat globules.