It is believed that the Chihuahua was derived from the -Techichi-, a small mute dog that the Toltecs of Mexico had since the 9th century.
It is generally an alert, plain-looking dog that is stronger than its small frame suggests. It has a rounded head, large erect ears, prominent eyes, and a compact body. The coat is variable in color and can be smooth and shiny or long and soft.
It is valued as an energetic companion especially suitable for apartment living. The American Kennel Club formally recognized the Chihuahua in 1904.

There are several types of Chihuahua, but they are actually mixtures of variations in color, coat, and size. Of the two main varieties, only one is recognized by the FCI and the AKC, this is the so-called -apple head-, the other: -deer head-, is accepted but not officially recognized.
In both varieties we can find specimens of multiple colors, solid and mixed; as well as short-haired, long-haired or hairless specimens (the latter very rare and disputed).
The so-called -mini- or -tea cups- are more common in the apple head variety, and the only requirement to be called that is that in their adulthood they must weigh less than 5 pounds and have a height of less than 9 inches.