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I'm a new Mac user and I've been installing a few different apps for different things. A lot of these use .dmg files.

Why exactly do they all expect me to drag the icon into the application folder? What is the point of this?

Drew
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    As Macs close the walls more and more (ex Mac App Store) you won't have to. It'll all be done for you... –  Jun 04 '11 at 22:50
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    @mankoff: How is making software easier to install and not adding any limitations as to how you can already install software "closing the walls"? – Mark Szymanski Jun 05 '11 at 03:18
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    @Mark Szymanski - Probably because the only way to get your app into the mac store is go through apple, and apple have a lot of limitations on what your software can and cannot do. – Fake Name Jun 05 '11 at 07:04
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    Mark, as much as I hate to say it, there are very significant functionality limitations enforced on apps submitted to the Mac App Store. – Jason Salaz Jun 05 '11 at 09:02
  • But still, that doesn't limit what you can already install through the normal methods. – Mark Szymanski Jun 05 '11 at 14:05
  • @Mark there are no limits yet on the desktop. Plenty on an iPad. Wait a while, I think the trend is clear... –  Jun 05 '11 at 18:58
  • @mankoff: Do you seriously think that Apple would ruin their OS by putting that limitation on it? – Mark Szymanski Jun 05 '11 at 19:33
  • Define 'ruin'. It isn't ruined if the majority of people want it, or think they want it, or Apple gets lucrative media deals because they can enforce better DRM. –  Jun 05 '11 at 20:54
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    This isn't a forum. Please keep it relevant to the original question. – David Metcalfe Jun 05 '11 at 22:19
  • Good to know there's still plenty of vitriol in the Mac community and it's not just limited to the Linux and Windows communities. Geeks are geeks after all. :) – Drew Jun 06 '11 at 14:42
  • Hi, I am from the future. @MarkSzymanski, it hurts to see your faith in '11. Why? Well, they did in fact ruin it. They seem to want us to use iOS. They also seem to feel free with these silent updates into the protected areas of the OS. They run their code on our hardware, in my homedir. It is an unforgivable sin. One of many. Woe betide us. Your future is a dystopia, and the robotic cars have not even started culling the weak yet. – chiggsy Aug 11 '19 at 23:17

6 Answers6

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An application on a Mac is just a folder full of files with a .app extension. However, macOS hides this fact from you and displays the folder as a file with an icon. Now when you download something it's very uncomfortable to download multiple separate folders (without a download manager). Therefore this "App Folder" has to be put inside a single file somehow. This is accomplished one of three ways:

  • Using a .zip file (a container that compresses its contents to save space)
  • Using a .dmg file (which is a flat file filesystem–as opposed to a hierarchical file system)
  • Make an installer (which, however, also has to be either in a .zip or .dmg because installers are folders on a mac, too)

Since most apps are self-contained and do not need anything outside of the app folder, an installer is not only overkill but also slower than just distributing the app folder.

You can obviously launch apps from wherever you want; it's only a custom or a recommendation to put them into /Applications as it easier for you to find it again and it works with multiple users.

Brad Turek
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XQYZ
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    No one has invented a .zip knock off that will automatically extract itself to the proper place (or a place of your choosing?) – Drew Jun 05 '11 at 01:13
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    Well there's self extracting stuff, but that's basically a dumbed down installer, which - again - is a folder on OS X. Also it's fairly insecure to just let it install wherever it wants to. I suppose apple could have just wrapped up a file extension (say .appzip) which would be just a renamed zip file, which extracts itself into /Applications when executed, but I don't exactly know why they didn't. Maybe it's just for historical reasons. – XQYZ Jun 05 '11 at 08:00
  • Regarding "or a place of your choosing": most extraction apps (The Unarchiver at least) can be configured to ask for a destination folder when extracting files. – XQYZ Jun 05 '11 at 08:03
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    @Drew think of this way: how is "automatically extracting itself to a proper place or a place of your choosing" any easier than giving a shortcut to the default (proper) place and allowing you to move it to any place of your choosing through using the OS own means? Well, I answer you: it's not. This is just a paradigm of what you're used to do. – cregox Jun 07 '11 at 13:34
  • XQYZ there's at least one added benefit of using DMG - it will keep file permissions as they were intended to be. I've had issues using ZIP to "install" software before, mostly because I was using an alternate unzipper app, but nevertheless even that's a risk DMG won't suffer. – cregox Jun 07 '11 at 13:39
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    @Cawas: Maybe it is just a paradigm thing, it's not exactly the hardest thing to do, but still. I have to click the installer, I have to click and drag the file, I have to close the mounted file system window, I have to unmount the file system and I have to delete the installer. As opposed to clicking the installer, clicking "OK" to put it in the default place, then deleting the installer.

    Again, not a huge deal, just a lot of stuff in my face that I didn't think would need to be there.

     – Drew Jun 07 '11 at 19:13
  • @Drew So the difference between an installer and a dmg with an app in it is simply copying the app to the /Applications directory. This answer (by XQYZ) states why apps are distributed as dmg format, so to answer the question, why do you expect you to drag/drop it? Because it's convention but not required. So they give you the option but you could put it wherever you want. An installer doesn't make sense because the developer doesn't know where you want to place the app. Installers are used when you need to write more files than just an app. – styfle Jun 17 '11 at 05:18
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    But why doesn't an installer just put it to the Applications folder – Code Name Jack Jun 18 '20 at 08:26
  • Thanks for explaining, but I still struggle to see how this makes any sense in the supposedly user friendly Apple world. For someone who just started using a Mac, it is not exactly user friendly to be presented with a window with two icons and an arrow between them. How is anyone supposed to know what this means or what they're supposed to do? At first I understood it as a strange way of telling me that the app is now installed (in the application folder). Isn't there at least a way of telling the user what they're supposed to do? – Christoph Jan 24 '21 at 16:37
  • Greetings from the future. It's 2023 and i still don't understand why i have to drag things to things, vs just say double clicking on the dmg file – Dusan Bosnjak 'pailhead' Sep 25 '23 at 15:37
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The /Applications folder is just a convenient place to store all of your applications. You can theoretically store them anywhere. Some software (such as Butler) will automatically search for applications in these standard locations, so if you store them elsewhere (such as /Users/Shared/Applications) such software won't find them by default.

Generally there are three standard places to store applications, and 99% of Mac users only work with the first one:

  • /Applications (available to all users)
  • /Users/username/Applications (available to the logged in user who owns that folder)
  • /Developer/Applications (available to all users, used for Xcode software)
Chuck
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You don't have to put your new Applications in the Application folder - it's just the default place to put them.

Rene Larsen
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You can create /Applications/Imaging, /Applications/Internet, etc. if you want categorize them. Just don't move any of the standard applications into these folders because further updates will expect them to be directly in /Applications.

nohillside
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clt60
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Keep in mind there are plenty of applications that assume they are in a folder called "Applications" and apps that looks for other specific apps in the "Applications" folder.

Chris Quenelle
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DMG files are compressed and read-only. Applications frequently need to be able to update or change components inside themselves; at a minimum, when a new version is detected and it offers to install an update - it won't be able to delete itself and put the new version in its place. Indeed, you'll probably find that running an application off a DMG will result in an "was downloaded from the internet" message on every launch. That doesn't happen if you move it to the right place.

Running an application off a locked DMG is a sure-fire way to run into problems. Just drag the application to some place on your hard disk - preferably one of the Applications folders.

There are certain locations on your Mac that have special significance to the system - these are places where the Mac goes looking for launchable applications when you double-click a document. They include the top level Applications folder, and a folder called "Applications" in your personal home folder. Mounted DMGs are not part of this, if only because they're not always mounted.

Xendo
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