One of the best ways to protect the files on your Mac is to enable FileVault. It is a feature of the Mac operating system (macOS) which performs on-the-fly encryption and decryption of all of your personal files when you save them and open them again. The beauty of FileVault is that this encryption and decryption occurs behind the scenes. All you have to do is enable it. Your interaction with your Mac won’t change. You’ll have the added protection without having to do anything differently. In the event that your Mac is stolen, a thief won’t be able to access your files. FileVault provides much more protection than merely using a password on your user account.

Below are a few caveats that you should read before you enable FileVault. Once you’re ready, you can follow Apple’s instructions for enabling FileVault.

Caveats:

1. FileVault requires you to enter your Mac user account password whenever you restart your Mac or wake it from sleep. Hopefully, you already have this security measure in place, but if not, you’ll be required to implement it now.
2. Enabling FileVault will slow down older Macs, especially those with spinning hard drives. If your Mac has a solid state drive (SSD) go ahead and enable FileVault. If your Mac has a spinning hard drive you may want to consider replacing it with a solid state drive (SSD), since they are noticeably faster and will let you enable FileVault without incurring such a large loss of performance.
3. It can take hours or even days to fully encrypt all of your data if you have an older Mac and hundreds of gigabytes (GB) on your hard drive. You can use your Mac while this encryption is taking place in the background, just be aware that you don’t gain the security advantages until the encryption process finishes.
4. FileVault is strong security. It provides significantly more protection than that provided by password-protecting your computer on your user account. The downside is that FileVault is strong security. If you forget your user account password, you could lose access to all of your data on your Mac. So please make sure you don’t lose or forget your password. Important: While enabling FileVault you’ll be prompted to setup an alternative way to regain access to your files should you ever forget your Mac user account password. The options vary based on which version of the Mac operating system (macOS) your Mac is running. With OS X 10.11 El Capitan and newer, you can use your AppleID password (aka iCloud password) to regain access to your Mac and your files. I recommend setting up a secondary access method, just to be safe.

FileVault is not a theft deterrent. However, in the event that your Mac is stolen and you have it enabled, the thieves won’t be able to access your files, which is a good thing. However, the thieves could erase your Mac and use the computer, thus FileVault is not a deterrent to stealing the computer. To get true theft deterrence you need a Mac that supports a feature called Activation Lock. This requires either a Mac with a T2 chip in it, which Apple started to introduce in some Macs in 2018, or any Mac using an Apple Silicon processor, like those Macs introduced in late 2020 with Apple’s M1 processor.