The automotive aftermarket is the secondary market of the automotive industry, concerned with the manufacturing, remanufacturing, distribution, retailing, and installation of all vehicle parts, chemicals, equipment, and accessories, after the sale of the automobile by the original equipment manufacturer (OEM) to the consumer. The parts, accessories, etc. for sale may or may not be manufactured by the OEM. According to a report by the International Trade Administration in the Department of Commerce, "Aftermarket parts are divided into two categories: replacement parts and accessories. Replacement parts are automotive parts built or remanufactured to replace OE parts as they become worn or damaged. Accessories are parts made for comfort, convenience, performance, safety, or customization, and are designed for add-on after the original sale of the motor vehicle." The aftermarket encompasses parts for replacement, collision, appearance, and performance, including electric propulsion. The aftermarket provides a wide variety of parts of varying qualities and prices for nearly all vehicle makes and models. Consumers have the option of repairing their vehicles themselves (the "do-it-yourself" or "DIY" segment) or can take the vehicle to a professional repair facility (the "do-it-for me" or "DIFM" segment). The aftermarket helps keep vehicles on the road by providing consumers the choice of where they want their vehicles serviced, maintained, or customized.

The United States automotive aftermarket is estimated to be worth $318.2 billion (2013), contributing more than 2.3% to GDP. The aftermarket employs 4.2 million people who work at manufacturers, distributors, retailers and repair shops. In the United States, online sales of aftermarket accessories have showed year over year increases over traditional brick and mortar stores. In fact, according to Hedges & Company, "Sales of auto parts & accessories continued to climb in 2015, and will continue the trend into 2016 to reach $7.4 billion dollars, posting around a 16% increase over 2015. Singapore, which does not have a domestic automobile industry, is an especially important destination for businesses exporting automotive parts and accessories due to its high automobile turnover stemming from the peculiarities of its driving laws. (In short, car owners are legally required to get rid of their cars after ten years of use and Singapore's compensation scheme to offset the registration fee of new cars has incentivized more frequent turnover.) High automobile turnover and the preference for new parts means that the market for remanufactured and reconditioned auto parts is very small. Combined with a high demand for "accessories, car-care products, prestige items, and new spare parts" (vehicle owners like to keep their cars in top condition), Singapore's automotive aftermarket is large. In fact, Singapore has become a major automotive components manufacturing base, as several leading multinational corporations (MNCs) have established international procurement offices as well as their Southeast Asia distribution centers. In Canada, the automotive aftermarket is a C$19.4 billion industry that employs about 420,000 people. In Australia, the automotive aftermarket industry in 2013 was estimated to generate a AUD$5.2 billion turnover, with 21000 staff, and 1400 manufacturers. Meeting platform for the international automotive aftermarket is the B2B trade fair Automechanika which takes place every two years in Frankfurt. At last edition the hot topics were connected cars, autonomous driving, alternative drives and the workshop of the future.

The automotive industry is a wide range of companies and organizations involved in the design, development, manufacturing, marketing, and selling of motor vehicles, some of them are called automakers. It is one of the world's most important economic sectors by revenue. The automotive industry does not include industries dedicated to the maintenance of automobiles following delivery to the end-user, such as automobile repair shops and motor fuel filling stations. The term automotive was created from Greek autos (self), and Latin motivus (of motion) to represent any form of self-powered vehicle. This term was proposed by Elmer Sperry.

The automotive industry began in the 1890s with hundreds of manufacturers that pioneered the horseless carriage. For many decades, the United States led the world in total automobile production. In 1929, before the Great Depression, the world had 32,028,500 automobiles in use, and the U.S. automobile industry produced over 90% of them. At that time the U.S. had one car per 4.87 persons.[3] After World War II, the U.S. produced about 75 percent of world's auto production. In 1980, the U.S. was overtaken by Japan and became world's leader again in 1994. In 2006, Japan narrowly passed the U.S. in production and held this rank until 2009, when China took the top spot with 13.8 million units. With 19.3 million units manufactured in 2012, China almost doubled the U.S. production, with 10.3 million units, while Japan was in third place with 9.9 million units. From 1970 (140 models) over 1998 (260 models) to 2012 (684 models), the number of automobile models in the U.S. has grown exponentially.