Guava is a common tropical fruit cultivated in many tropical and subtropical regions. The common guava Psidium guajava is a small tree in the myrtle family (Myrtaceae), native to Mexico, Central America, the Caribbean and northern South America. The name guava is also given to some other species in the genus Psidium such as strawberry guava and to the pineapple guava, Feijoa sellowiana. In 2019, 55 million tonnes of guavas were produced worldwide, led by India with 45% of the total. Botanically, guavas are berries.

Myrtaceae, the myrtle family, is a family of dicotyledonous plants placed within the order Myrtales. Myrtle, pōhutukawa, bay rum tree, clove, guava, acca (feijoa), allspice, and eucalyptus are some notable members of this group. All species are woody, contain essential oils, and have flower parts in multiples of four or five. The leaves are evergreen, alternate to mostly opposite, simple, and usually entire. The flowers have a base number of five petals, though in several genera, the petals are minute or absent. The stamens are usually very conspicuous, brightly coloured, and numerous.