Autorun vs Autoplay – What’s the Difference?

Posted on June 9, 2010 at 5:31 am

One question I’ve been getting a lot recently is what exactly is the difference between Autoplay and Autorun? These are two terms that are actually pretty confusing. When someone first asked me a year ago, I didn’t even know myself!

Most people think Autorun and Autoplay are just two terms for the same thing. However, that is not true. Firstly, it’s a good idea to know when they actually came out.

Autorun was the first to show up way back in Windows 95! What was the point of it exactly? To make installing apps for non-techies easier. If a CD contained a file called autorun.inf in the root directory, Windows would detect it automatically and follow the instructions in that file.

Normally, this file would call an application on the CD, usually the setup file or install file. You’ve probably noticed this when you pop in a new Windows XP or Windows 7 CD into your computer, a splash screen will automatically pop up with options to install Windows, etc.

Autoplay is a feature that was only introduced in Windows XP. Autoplay’s job is to examine a newly connected media device, determine what kind of content is on it, and then display a dialog that allows the user to launch an application to play or display the content.

Now here is where it gets complicated! Depending on the operating system you are running, Autorun and Autoplay will work differently! And that’s why everyone is normally confused as to how it all works.

In all versions of Windows from XP to Windows 7, Autorun is executed before Autoplay, unless Autorun is disabled. If it’s not disabled, Autorun will execute and it will search for the Autorun.inf file.

In Windows XP, if the Autorun.inf file is found, Autorun can go ahead and bypass Autoplay altogether and launch an application without asking the user first.

In Windows Vista and Windows 7, Autorun cannot skip past Autoplay. If there is an Autorun.inf file, it will still be read, but instead of the application being launched automatically, a dialog box will pop up with a list of choices, some of which could be from the Autorun.inf file. Gone mad yet?

To make this totally clear, let’s go through an example. I have an Office 2003 CD with me that I will pop into Windows XP and Windows 7, both with Autorun and Autoplay enabled.

Here is what the Autorun.inf file looks like on the Office 2003 CD:

autorun inf

Basically, it says that the setuppro.exe file should automatically be launched when Windows detects the CD in the drive. Simple enough.

In Windows XP, when I pop the CD in, since there is an Autorun.inf file, I don’t get any Autoplay options and the Office setup automatically starts!

autorun vs autoplay

However, when I pop the same CD into Windows 7 (or Windows Vista), I instead get the Autoplay dialog box:

autoplay windows 7

So even though there is an Autorun.inf file, the program is not allowed to execute until I decide. Also note that the option to run setuppro.exe is also listed in the Autoplay dialog box because it read that from the Autorun.inf file.

Overall, the Autoplay feature is not going to harm your computer because no program is actually being executed. All Autoplay does is detect the media and display options.

If you’re running Windows XP, it might be a good idea to disable Autorun because on that operating system, programs can still be run without user consent.

On Windows 7 and Vista, you don’t have to worry about it as much because Autorun cannot bypass Autoplay, so everything goes through Autoplay before it is executed.

Hopefully that clears up the confusions about the differences between Autorun and Autoplay! If you still have questions, post a comment here and I’ll try to help. Enjoy!

» Filed Under Computer Tips

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Comments

3 Responses to “Autorun vs Autoplay – What’s the Difference?”

  1. Chandrashekhar said on : June 9th, 2010 at 6:27 am

    Thanks for publishing this useful post. Many peoples are not able to distinguish the difference between Autorun and Autoplay.


  2. Sil said on : October 25th, 2010 at 8:15 am

    Hi Sir

    I have a question for you.. my USB has an application that automatically installed using autorun and now there is a virus on the USB stick.. for you.. what will first be read by the computer: the autorun file or the virus? which of them the first to execute when plugged into the computer?

    thank you sir…

    i appreciate your post about autorun and autoplay it is a big help for us..


  3. frozenfire said on : November 3rd, 2010 at 5:41 pm

    Thank you very much sir this really helps a lot…I didn’t understand the difference between autorun and autoplay before.


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