They are native to Mexico, the Caribbean, Central America and the northern part of South America. Now they are found in all the tropical, and in some subtropical, regions because they are edible fruits.
Guava are also a kind of berry fruit on those plants. There are many kinds of guavas. The most common guava is the apple guava (Psidium guajava): it is so common that the word 'guava' usually refers to this species. Red guavas are called maroonguava. In 100 g of guava are 200 mg of vitamin C, which means that guavas have five times more vitamin C than oranges.
Guava's are very good.