AutoRun is a programming system used in certain versions of Windows™ operating systems (OS) that allows the system to automatically install a new program for the user. This is in contrast to early versions of the OS and some other OS programs that require the computer user to actively make an effort to install a program onto a computer. The process is typically utilized with a compact disc (CD) or other hardware that is used to install a program onto a computer. AutoRun allows the OS to detect the presence of an installation on such hardware and then allows the program to be easily installed onto the computer.
Sometimes used synonymously with AutoPlay, AutoRun is not actually the same. AutoPlay was used synonymously in earlier versions of OS programs, but it has since been established as a separate functionality that automatically plays media files. AutoRun, on the other hand, works to automatically install programs and does not affect discs or other formats that contain media data such as videos and music.
When a device is connected to a computer that contains a program, such as a CD inserted into a drive on a computer or a flash drive inserted into a port on the computer, then the computer OS will typically detect that device. This causes a device notification to be sent to the OS, which in turn begins the AutoRun process. The process begins with the OS detecting if AutoRun has been disabled on the computer; if it has, then the process should go no further.
As long as AutoRun is enabled on the computer, the OS looks for an AutoRun file in the root directory of the program on the media. This file allows the OS to easily run and install the program. A notification window will typically pop up on the desktop for the user, indicating that the program will install automatically, allowing the user to cancel the installation or approve it. Beyond this, the user does not necessarily have to interact with the installation at all, though most programs will also provide an end user license agreement (EULA) that must be accepted and may allow the user to alter some aspects of the installation.
Without this type of feature in the OS of a computer, programs must be manually installed. Some computer users prefer this, allowing them to more easily control when and where programs are installed, and this typically requires little effort. In earlier versions of OS, however, the advantages of automatic installations were far greater, and the process was introduced to reduce technical support questions from customers regarding installation of programs.