An assembly line is a manufacturing process (often called a progressive assembly) in which parts (usually interchangeable parts) are added as the semi-finished assembly moves from workstation to workstation where the parts are added in sequence until the final assembly is produced. By mechanically moving the parts to the assembly work and moving the semi-finished assembly from work station to work station, a finished product can be assembled faster and with less labor than by having workers carry parts to a stationary piece for assembly.

Assembly lines are common methods of assembling complex items such as automobiles and other transportation equipment, household appliances and electronic goods.

Workers in charge of the works of assembly line are called assemblers.

The Ford Model T is an automobile that was produced by Ford Motor Company from October 1, 1908, to May 26, 1927. It is generally regarded as the first affordable automobile, which made car travel available to middle-class Americans. The relatively low price was partly the result of Ford's efficient fabrication, including assembly line production instead of individual handcrafting. The Model T was colloquially known as the "Tin Lizzie," "Leaping Lena" or "flivver".The Ford Model T was named the most influential car of the 20th century in the 1999 Car of the Century competition, ahead of the BMC Mini, Citroën DS, and Volkswagen Beetle. Ford's Model T was successful not only because it provided inexpensive transportation on a massive scale, but also because the car signified innovation for the rising middle class and became a powerful symbol of the United States' age of modernization. With 15 million sold, it was the most sold car in history before being surpassed by the Volkswagen Beetle in 1972, and still stood eighth on the top-ten list, as of 2012.