Mac User Guide
- Welcome
- What’s new in macOS Tahoe
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- Intro to Apple Intelligence
- Translate messages and calls
- Create original images with Image Playground
- Create your own emoji with Genmoji
- Use Apple Intelligence with Siri
- Find the right words with Writing Tools
- Summarize notifications and reduce interruptions
- Use ChatGPT with Apple Intelligence
- Apple Intelligence and privacy
- Block access to Apple Intelligence features
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- Intro to Continuity
- Use AirDrop to send items to nearby devices
- Hand off tasks between devices
- Control your iPhone from your Mac
- Copy and paste between devices
- Stream video and audio with AirPlay
- Make and receive calls and text messages on your Mac
- Use your iPhone internet connection with your Mac
- Share your Wi-Fi password with another device
- Use iPhone as a webcam
- Insert sketches, photos, and scans from iPhone or iPad
- Unlock your Mac with Apple Watch
- Use your iPad as a second display
- Use one keyboard and mouse to control Mac and iPad
- Sync music, books, and more between devices
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- Get started
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- Accessibility features for vision
- Get started with VoiceOver
- Zoom in on what’s around you
- Zoom in on your Mac screen
- Increase font size and icons
- Adjust the display colors
- Hover to zoom in on text and colors
- Listen to or change how text appears in apps
- Customize onscreen motion
- Increase the size of what’s on your screen
- Make the pointer easier to see
- Have your Mac speak text that’s on the screen
- Resources for your Mac
- Resources for your Apple devices
- Copyright and trademarks
Learn about your Mac computer’s internal disk
Your Mac has an internal disk, which is a storage device that contains the apps and information used by your Mac. Some Mac computers have additional internal disks or connected external disks.
Specify a startup disk
The startup disk contains the macOS system software. Your internal disk is usually the startup disk, but you can also start up your Mac from a network disk or an external disk that has system software on it. See Change your Mac startup disk.
Important: If you have a Mac with an Apple T2 Security Chip, added security features may be set to prevent the computer from starting up from an external startup disk. See What is the Startup Security Utility? If you have a Mac with Apple silicon, see Change the security policy.
To find out which disk is being used as the startup disk, choose Apple menu 
in the sidebar, then click Startup Disk on the right (you may need to scroll down).
Manage disk space
To see how much space is available on a disk, open a Finder window, select the disk in the Locations section of the Finder sidebar, choose File > Get Info, then click 
next to General. To increase available space, you can compress folders, delete personal items, or store items on a separate disk. See Optimize storage space.
Divide your internal disk into different sections
You can divide a single disk into sections, called partitions or volumes, or containers that act like smaller disks. Some people do this to help organize and manage their disk space. You can create or remove APFS volumes using Disk Utility.
Back up your disk information
It is very important to regularly back up the files on your internal disk. Time Machine makes backing up easy. See Back up your files with Time Machine.
Troubleshoot disk problems
If you suspect or experience problems with your internal disk, Disk Utility can help you diagnose and repair problems. Be sure to follow instructions carefully.
If necessary, a faulty hard disk drive (HDD) can be replaced. For service information, see Find out how to service or repair your Mac.