The tomato (Solanum lycopersicum, syn. Lycopersicon lycopersicum & Lycopersicon esculentum"Molecular phylogenetic analyses have established that the formerly segregate genera Lycopersicon, Cyphomandra, Normania, and Triguera are nested within Solanum, and all species of these four genera have been transferred to Solanum." See: Natural History Museum, Solanaceae Source: Phylogeny of the genus Solanum.) is an herbaceous, usually sprawling plant in the Solanaceae or nightshade family, as are its close cousins potatoes, chili peppers, tobacco, aubergine and the poisonous belladonna. It is a perennial, often grown outdoors in temperate climates as an annual. Typically reaching to in height, it has a weak, woody stem that often vines over other plants. The leaves are long, odd pinnate, with 5–9 leaflets on petioles, each leaflet up to long, with a serrated margin; both the stem and leaves are densely glandular-hairy. The flowers are across, yellow, with five pointed lobes on the corolla; they are borne in a cyme of 3–12 together.

The tomato is native to South America. Genetic evidence shows that the progenitors of tomatoes were herbaceous green plants with small green fruit with a center of diversity in the highlands of Peru. These early Solanums diversified into the dozen or so species of tomato recognized today. One species, Solanum lycopersicum, was transported to Mexico where it was grown and consumed by prehistoric humans. The exact date of domestication is not known. Evidence supports the theory the first domesticated tomato was a little yellow fruit, ancestor of L. cerasiforme,Fact: date=February 2009 grown by the Aztecs of Central Mexico who called it ‘xitomatl' (pronounced IPA2: ʃiːtomatɬ), meaning plump thing with a navel, and later called tomatl by other Mesoamerican peoples. Aztec writings mention tomatoes were prepared with peppers, corn and salt, likely to be the original salsa recipe.

Some people believe that the Spanish explorer Cortez may have been the first to transfer the small yellow tomato to Europe after he captured the Aztec city of Tenochtítlan , now Mexico City in 1521. Yet others believe Christopher Columbus, an Italian working for the Spanish monarchy, discovered the tomato earlier in 1493. The earliest discussion of the tomato in European literature appeared in an herbal written in 1544 by Pietro Andrea Mattioli, an Italian physician and botanist, who named it pomi d'oro, golden apple.

The word tomato comes from a word in the Nahuatl language, tomatl. The specific name, lycopersicum, means "wolf-peach" (compare the related species Solanum lycocarpum, whose scientific name means "wolf-fruit", common name "wolf-apple"), as they are a major food of wild canids in South America.Fact: date=February 2009