Installing apps under Mac OS X is fairly straightforward, but takes a somewhat different approach to the model Windows users are familiar with. Here's the three methods you're most likely to encounter.
Mounting a disk image
This is the standard official method, whether you're downloading files from online or (more rarely these days) installing from disk. What you'll end up with in either case is a file named appname.dmg (with appname replaced by the name of the software you're installing). If you've downloaded a compressed file in .zip format, you can double-click on it to extract the enclosed file.
To install the app from a disk image file:
- Double-click on the .dmg file (in Finder or your browser if it has a download window).
- Follow the instructions in the dialog box that appears which tells you to drag the app icon into the Applications folder. If you instead end up with a file windows with a .app file in it, drag that file into the Applications folder in Finder (which is available either in Finder or at the right-hand side of your Dock at the bottom of the screen.).
- That's basically it -- you can now run the application from the Applications folder
- If you've downloaded an application from online, you'll receive a security warning the first time you try to run it. If there are any preferences to be set before you can use the app, these will also often appear when you first run it.
Using the Mac App Store
Launched in early 2011, the Mac App Store is an alternate installation method that essentially copies the iTunes-based installation system used for iPhones and iPads. (The App Store itself appears by default in your Dock; it's the one with the giant A on it.) It's widely assumed that this method will eventually be promoted as Apple's main way to install applications.
If you're familiar with iTunes, this isn't a difficult system to master: just locate the app you want within the App Store, and click on either the 'Install' or 'Free' buttons (depending on if it's a paid app). The app will then install itself automatically (and add itself to your Dock).
Note that even for free apps, you'll need an Apple ID. The App Store also automatically tracks updates for apps which you have purchased or acquired through it.
Windows-like app installers
Some software will take a more Windows-like approach to installation, using a wizard to step through the process (the Mac version of Office and Telstra's mobile broadband client are examples). This is atypical, but if you're familiar with Windows, not especially difficult to come to grips with.
MacBook Migrant is a week-long series of posts highlighting tricks new or aspiring Mac owners familiar with Windows can use to ease the transition.