When people find out that a tomato is a fruit, not a vegetable, they are usually surprised. They think of fruits as being sweet and vegetables as being savory. Since tomatoes are commonly used in savory dishes, why aren't they called vegetables?
The answer is simple. What distinguishes a fruit from a vegetable isn't whether it is sweet or not. It has to do with which part of the plant we eat.
Botanically speaking, a fruit is the fleshy part of the plant that surrounds a seed or seeds. So apples, peaches, plums, grapes, pears and bananas, which we commonly call "fruits," indeed are. And so are tomatoes, peppers, cucumbers and squashes.
A vegetable's edible parts are its leaves, stems or roots. So lettuce and spinach are vegetables, because we eat the leaves. Asparagus is a vegetable - we eat the stems. And beets, carrots, potatoes and onions are vegetables, because they are "root crops."
That's your botany lesson for today.