Rent-a-car (car hire in British English) is a company that rents automobiles for short periods of time (ranging from a few hours to a few weeks) for a fee. It is an elaborate form of a rental shop, organized in numerous local branches, primarily located near airports or busy city areas. The internet is changing the car rental industry with companies that are now called online car rental companies.

Car rental agencies primarily serve people who have a car that is temporarily out of reach or out of service, for example travellers who are out of town or owners of damaged or destroyed vehicles who are awaiting repair or insurance compensation. Because of the variety of sizes of their vehicles, car rental agencies may also serve the self-moving industry needs, by renting vans or trucks.

Car rentals are subject to many conditions which vary from one brand to another. The vehicle must be returned in a good condition and must not exceed a maximum driven distance, otherwise extra fees may be incurred. Additionally, some companies set up a minimum age for the vehicle driver, which in some cases is as high as 25, even in countries where the minimum legal age to hold a driver's license is much lower. Recent conditions have utilised GPS technology to limit maximum speeds or driving to specific regions.