Computer reservation systems, or central reservation systems (CRS), are computerized systems used to store and retrieve information and conduct transactions related to air travel, hotels, car rental, or other activities. Originally designed and operated by airlines, CRSs were later extended for use by travel agencies, and global distribution systems (GDSs) to book and sell tickets for multiple airlines. Most airlines have outsourced their CRSs to GDS companies, which also enable consumer access through Internet gateways.

A car rental, hire car or car hire agency is a company that rents automobiles for short periods of time to the public, generally ranging from a few hours to a few weeks. It is often organized with numerous local branches, and primarily located near airports or busy city areas and often complemented by a website allowing online reservations.