How To Reinstall Mac OS on Your Mac

No matter how good a computer is built, they all come to a point where necessary maintenance must be performed. The same goes for Mac computers. They may not contract viruses, but they can lose some functionality, and one of the simplest ways to counteract this is to reinstall the Operating System for your Mac device.

Important Note:

This process does not necessarily run the risk of wiping your data, but it is ALWAYS good practice to back everything up just in case. The process is helpful, but it is not without its flaws so be prepared. Here are the most common ways to back up your computer.

  • A properly formatted Flash Drive is a common means to back up documents, photos, and music files, depending on how big they are.

  • External Hard Drive can clone your entire database.

  • Time Machine (Apple menu > System Preferences > Time Machine). You will be able to back up your entire file including games and other large programs.

  • iCloud (System Preferences > iCloud). You will be able to back up your important documents, photos, etc. and it can all be retrieved from any Mac Computer through your Apple ID.

  • Time Capsule

  • You can also make a compressed back up using the Mac’s disk utility

Reinstallation of Mac OS

Once you have backed up your data, you’ll be ready to begin the reinstallation process. You can either use the Mac Recovery Mode or Mac Internet Recovery Mode. The first mode will set up the last OS version installed prior to beginning this procedure and won’t cause any data loss—though you should still back up your data. This cannot be stressed enough.

The second mode is best used for when selling your device, as it will install the original OS that was present when the computer was first purchased. It will erase all of your data and restore the device’s factory settings. If you want to delete the data anyway, you can do that manually through the Disk Utility.

The computer must be connected to the Internet regardless of which mode you choose to use, and while that decision is yours to make, for the purpose of this article, we will use Method One: Mac Recovery Mode. Mac Internet Recovery Mode will be explained some near the end.

Steps for Mac Recovery Mode

  1. Restart or turn on your Mac. You can do this through the command menu (Apple Logo) at the top left corner of your desktop screen or by pressing/holding the power button.

  2. As soon as your Mac starts up, press and hold the Command and R keys until you see the Apple logo.

  3. Once the Apple logo appears on the screen, and you hear the first chime, release the buttons.

  4. You will now be brought to the Utilities Window.

  5. You will be prompted to select “Reinstall Mac” (or possibly “Reinstall OS X). Once you do, click “Continue” and follow the guidelines.

  6. This process will reinstall your most recent version of the Mac OS. For instance, if you were running El Capitan prior to this reboot, your computer will reinstall El Capitan.

  7. You will then be taken through the process of connecting your device to the Internet via Wi-Fi. If you do not or cannot connect now, the process will be halted until you can be.

  8. From here, a new window will appear informing you that “To download and install mac OS, your computer’s capability will be tested with Apple.” This is why it is important to be connected to the Internet. Click Continue. 

  9. Agree to the terms and conditions to continue.

  10. Finally, choose your hard drive (in this case, Macintosh HD), and lastly, click Install.

Giving Away Your Mac

You can completely delete your data prior to installing the Mac OS. This is only necessary if you are about to give the computer to a new owner, and you want the device in “like new” condition. You will want to use the Mac Internet Recovery Mode. The steps for this are the same except step two, which becomes “press and hold the Option-Command-R keys until you see the Apple logo.” This installation won’t have your Apple ID connected to it.

All Done

And you’re done. Nothing left but to use that fresh “like new” Mac.

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