The name of this batch file comes from a combination of the words automatically executed batch file. Like other batch files, AUTOEXEC.BAT contains a series of DOS commands that your (IBM-compatible) PC runs for you, one after the other, so that you don't have to type the commands individually. It gives the computer various basic instructions about starting Windows, running antivirus checks in the background, identifying the keyboard, and so on.
The file was typically used to issue configuration and initialization commands to the operating system and PERIPHERAL devices such as CD-ROM drives and sound cards, a typical entry being. What's special about AUTOEXEC.BAT is just that DOS automatically runs this particular batch file each time you turn on or restart the computer. Most people wind up calling AUTOEXEC.BAT the "AUTOEXEC" file for short.
AUTOEXEC.BAT must be stored in the ROOT DIRECTORY of the computer's BOOT DRIVE in order to be found and executed, and the commands it contains follow the same syntax as any other MS-DOS BATCH File, that is, a list of operating system commands exactly as they would be typed manually at the COMMAND PROMPT, plus certain control structures such as GOTO that cannot be deployed manually.
You can customize the AUTOEXEC file yourself, filling it with exactly the commands you want to get your system up and running to your specifications and to suit the needs of your software and peripherals. AUTOEXEC.BAT is typically used to set the look of the DOS prompt, tell DOS which directories it should search when looking for programs to run, configure the serial ports, load the mouse driver, and start memory resident programs and utilities. If you like, you can use the AUTOEXEC file to start a particular application program (such as your word processor) or to start Windows.
Here's an excerpt from a typical AUTOEXEC.BAT file:
PATH=C: \ WINDOWS;C: \DOS;C: \ UTILS
SET TEMP=D: \ TEMP
These lines set the DOS prompt to show the current directory; set the DOS path; and tell the system to look for temporary files in the D: \ TEMP directory.
The process of starting or restarting a computer. Boot is a process that the computer goes through to get ready to receive input. During this boot process, certain configuration files, such as the AUTOEXEC.BAT, are used. For example, at startup, the commands in AUTOEXEC.BAT are executed one at a time automatically, without the user typing them in.
A type of executable file that contains a "batch" or listing of DOS commands to be executed in order, as if the user had typed each one in separately. One example of a batch file is the AUTOEXEC.BAT, whose instructions are executed whenever the system is booted.
A symbol that indicates DOS is ready for the next command. The DOS prompt generally looks like C:\>, but it can be changed by commands in AUTO.EXEC.BAT.