The tomato is a plant in the Solanaceae or nightshade family. Originating in South America, the tomato (Lycopersicon lycopersicum and L. esculentum) is now grown world-wide for its brightly coloured (usually red, from the pigment lycopene) edible fruits. The word "tomato" is of Nahuatl origin.
In the 16th and 17th centuries, many Europeans believed tomatoes were poisonous, because of the plant's relationship to nightshade and tobacco, although they were grown as garden ornamentals. There is a story that a man in Spain once sold tickets for spectators to observe him eating tomatoes; the spectators expected to see him die a horrible death but were disappointed. This misapprehension has been banished, and tomatoes are now eaten freely in Europe as well as the rest of the world. In the past it has also periodically been esteemed as a purported aphrodisiac; today, its consumption is believed to benefit the heart.
Botanically a berry, the tomato is generally thought of--and used--as a vegetable: it's more likely to be part of a sauce or a salad than eaten whole as a snack, let alone as part of a dessert (though, depending on the variety, they can be quite sweet, especially roasted).
Used extensively in most Mediterranean cuisines, especially Italian ones. The tomato has an acidic property that is used to bring out other flavors.
The town of Buñol, Spain annually celebrates La Tomatina, a festival centered on an enormous tomato fight.