The avocado is a pear-shaped, edible fruit that grows on a tree. It has a greenish black leathery outer skin, a soft light-green inner fruit, and a single large seed called a pit in America or a stone in Britain. The outer layer is easily peeled from the fruit and in most varieties turns from a green color to greenish black as it ripens.
There are many varieties of avocado, some of the most popular are the: Hass, Fuerte, Bacon, Gwen, Lamb Hass, Pinkerton, Reed, and Zutano. All are similar in size, appearance and taste. Avocados have a mild taste and can be eaten raw, or cooked in other foods. "Guacamole" is a popular dip that is made from avocado. 
The avocado is rich in Vitamins A and C, B vitamins, glutamine and potassium, and has low sodium and no cholesterol. A medium avocado contains on average about 180 calories, 4 grams of protein, 10 grams of fiber, and about 5 grams of fat.  
Avocados are sometimes called alligator pears because of their shape and the color of their skin.
Avocados are commonly grown throughout Mexico and South America. In the United States, California is the leading avocado producer in the nation. An avocado tree will normally bear fruit after two or three years, and a mature tree will produce on average around 60 pounds (about 150 pieces) of fruit each year.