Chipotle

[Chee-POT-tleh] peppers are smoked jalapeno chili peppers and are also known as chili ahumado.
These chilies are usually a dull tan to coffee color and measure approximately 2 to 4 inches in length and about an inch wide. As much as one fifth of the Mexican jalapeno crop is processed into chipotles

History
Chipotles date back to region that is now northern Mexico City, prior to the Aztec civilization. It is conjectured that the Aztecs smoked the chilies because the thick, fleshy, jalapeno was difficult to dry and prone to rot. The Aztecs used the same "smoke drying" process for the chilies as they used for drying meats. This smoking allowed the chilies to be stored for a substantial period of time.

Today Chipotles are used widely throughout Mexico as well as in the United States. Quite popular in the South Western U.S. and California; Chipotles have found their way into the cuisine of many celebrity chefs from Hawaii to Manhattan.
Varieties
Smoked Whole Chilies
Chile ahumado pictured at the top of this page, (also referred to as "tipico" and "chile meco" - is greyish tan in color with a very rich smoky flavor. It is said to resemble a "cigar butt" in shape. This "authentic" preferred Chipotle.

Morita, pictured below, means "little blackberry" in Spanish. The chili is dark reddish purple. This is the variety most often found in the United States. While it is quite flavorful it is not smoked as long as the ahumado and therefore not of the same high quality and cheaper to produce. Many of the varieties sold as "tipico" in the U.S. are actually the inferior "morita". It's important to note that although the Morita is considered "inferior" compared to the much less common ahumado, or tipico, it is still a delicious and useful product.