A 19-inch rack is a standardized frame used to hold electronic equipment, such as servers, networking devices, and audio-visual gear. The term "19-inch" refers to the width of the equipment that fits into the rack, which is measured from the outer edges of the mounting brackets. This design allows for efficient organization and cooling of devices in data centers and server rooms. These racks typically have vertical rails spaced 1.75 inches apart, allowing for the installation of various components in a modular fashion. Commonly used in conjunction with rack-mounted servers and network switches, 19-inch racks help optimize space and improve accessibility for maintenance and upgrades.