The term "mustang" can refer to two different things. The first is a free-roaming horse of the Western United States, descended from horses brought to the Americas by the Spanish. Mustangs are often referred to as wild horses, but because they are descended from once-domesticated animals, they are actually feral horses. The original mustangs were Colonial Spanish horses, but many other breeds and types of horses contributed to the modern mustang, now resulting in varying phenotypes. The second is a series of American automobiles manufactured by Ford, known as the Ford Mustang. The Mustang is a highly styled line of sporty coupes and convertibles derived from existing model lines, initially distinguished by "long hood, short deck" proportions. It has been in continuous production since 1964 and is currently the longest-produced Ford car nameplate. The Mustang has gone through several generations and has had multiple nameplates associated with it, including GT, Mach 1, Boss 302/429, Cobra, and Bullitt.