You can connect an optional USB accessory to replace the missing drive, of course. In many instances, you can download new programs directly from the Internet. And the Mac App Store makes it a breeze to fetch programs that you buy there.
Still, you may have come upon installation discs that are required to load older programs (and possibly new ones as well). Even without a built-in disk drive, you figure that there must be a way to install the software.
You figure right, at least if you have an available DVD or CD drive on another computer, whether that computer is a Mac or even a Windows PC. That other machine must be connected to the same network as the Mac on which you want to load software. Also, your Mac must support the Remote Disc feature, but the good news is that all the recent models do.
Proceed as follows: If the optical drive you’re sharing is on a Mac, open System Preferences, choose Sharing, and select the check box for DVD or CD Sharing. At your discretion, also select the Ask Me Before Allowing Others to Use My DVD Drive check box. Place the DVD in the drive you’re sharing from and then go to the Mac that doesn’t have an optical drive.
On that computer, open a Finder window, and select Remote Disc on the Sidebar. You should see an icon for the computer that has the optical drive. Double-click the icon, and click Connect. Click Ask to Use if the other computer chose the aforementioned Ask Me option. The other computer must then accept your request. Assuming that this happens, you can install the program as though the optical drive were local to the computer that’s gaining the new software.
If the optical drive you’re sharing from is on a Windows PC, you must download DVD or CD Sharing Update 1.0 for Windows. Then enable DVD or CD Sharing in the Hardware and Sound section of Control Panel. Back on your Mac, open a Finder window, and proceed as before.