Guava is native to the warm regions of the Americas stretching from Mexico to Peru. Although the guava plant was domesticated more than 2,000 years ago, it was not until 1526 when the first commercial cultivation of guava was reported in the Caribbean islands. Later it was spread by explorers into the Philippines and India. From there it quickly spread to most of the tropical and subtropical regions of the world where it has become naturalized to the point that in certain areas it is considered a noxious weed. 

Ripe guava fruit is an excellent source of ascorbic acid (vitamin C) and dietary fiber. Guava is also a good source of vitamin A, phosphorus, calcium and iron as well as thiamine and niacin. Reportedly, consumption of guava fruit reduces serum cholesterol levels, triglycerides and hypertension while increasing the level of good cholesterol (high
density lipoprotein). 

Guava can be eaten as fresh fruit when ripe, prepared into sauce and chutney, or cooked as a vegetable when green. It can be processed for jam, jelly, nectar and fruit juices as well as flavoring for other foods. There are processing and fresh fruit or dessert varieties of guava with white, salmon red, or pink flesh and light green to yellow skin colors. The
average diameter of fruit varies from 1.6 to 4.0 inches and weight may range 5 to 14 oz.

Here are some good guava sites:
http://agrolink.moa.my/comoditi/guava/guava.html

http://recipes.wenzel.net/c/caribbean_guava_punch.html

http://www.hort.purdue.edu/newcrop/morton/guava.html#Description