OS X is Apple's operating system that runs on Macintosh computers. It was first released in 2001 and over the next few years replaced Mac OS 9 (also known as Mac OS Classic) as the standard OS for Macs. It was called 'Mac OS X' until version OS X 10.8, when Apple dropped 'Mac' from the name.
OS X was originally built from NeXTSTEP, an operating system designed by NeXT, which Apple acquired when Steve Jobs returned to Apple in 1997. Like NeXTSTEP, OS X is based on Unix and uses the same Mach kernel. This kernel provides OS X with better multithreading capabilities and improved memory management compared to Mac OS Classic. While the change forced Mac developers to rewrite their software programs, it provided necessary performance improvements and scalability for future generations of Macs.
The OS X desktop interface is called the Finder and includes several standard features. OS X does not have a task bar like Windows, but instead includes a menu bar, which is fixed at the top of the screen. The menu bar options change depending on what application is currently running and is only hidden when full screen mode is enabled. The Finder also includes a Dock, which is displayed by default on the bottom of the screen. The Dock provides easy one-click access to frequently used applications and files. The Finder also displays a user-selectable desktop background that serves as a backdrop for icons and open windows.
When you start up a Mac, OS X loads automatically. It serves as the fundamental user interface, but also works behind the scenes, managing processes and applications. For example, when you double-click an application icon, OS X launches the corresponding program and provides memory to the application while it is running. It reallocates memory as necessary and frees up used memory when an application is quit. OS X also includes an extensive API, or library of functions, that developers can use when writing Mac programs.
Linus Torvalds developed the Linux kernel and distributed its first version, 0.01, in 1991. Linux was initially distributed as source code only, and later as a pair of downloadable floppy disk images – one bootable and containing the Linux kernel itself, and the other with a set of GNU utilities and tools for setting up a file system. Apple's Mini DisplayPort adapters work with Mac models that have a Mini DisplayPort, Thunderbolt port, or Thunderbolt 2 port when using Mac OS X Leopard 10.5.6 or later: These adapters don't work with the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter, which doesn't support Mini DisplayPort displays.
While the OS X interface remains similar to the original version released in 2001, it has gone through several updates, which have each added numerous new features to the operating system. Below is a list of the different versions of OS X, along with their code names.
- Mac OS X 10.0 (Cheetah)
- Mac OS X 10.1 (Puma)
- Mac OS X 10.2 (Jaguar)
- Mac OS X 10.3 (Panther)
- Mac OS X 10.4 (Tiger)
- Mac OS X 10.5 (Leopard)
- Mac OS X 10.6 (Snow Leopard)
- Mac OS X 10.7 (Lion)
- OS X 10.8 (Mountain Lion)
- OS X 10.9 (Mavericks)
- OS X 10.10 (Yosemite)
Updated: December 31, 2014
Disk Utility can find and repair errors related to the formatting and directory structure of a Mac disk. Errors can lead to unexpected behavior when using your Mac, and significant errors might even prevent your Mac from starting up completely.
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Before proceeding, make sure that you have a current backup of your Mac, in case you need to recover damaged files or Disk Utility finds errors that it can't repair.
Open Disk Utility
In general, you can just open Disk Utility from the Utilities folder of your Applications folder. However, if your Mac doesn't start up all the way, or you want to repair the disk your Mac starts up from, open Disk Utility from macOS Recovery:
- Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:
- Apple silicon: Turn on your Mac and continue to press and hold the power button until you see the startup options window. Click the gear icon labeled Options, then click Continue.
- Intel processor: Turn on your Mac, then immediately press and hold these two keys until you see an Apple logo or other image: Command (⌘) and R.
- You may be asked to select a user you know the password for. Select the user, then click Next and enter their administrator password.
- From the utilities window in macOS Recovery, select Disk Utility and click Continue.
Select your disk in Disk Utility
Choose View > Show All Devices (if available) from the menu bar or toolbar in Disk Utility.
Disk Utility can find and repair errors related to the formatting and directory structure of a Mac disk. Errors can lead to unexpected behavior when using your Mac, and significant errors might even prevent your Mac from starting up completely.
Dis Mac Os X
Before proceeding, make sure that you have a current backup of your Mac, in case you need to recover damaged files or Disk Utility finds errors that it can't repair.
Open Disk Utility
In general, you can just open Disk Utility from the Utilities folder of your Applications folder. However, if your Mac doesn't start up all the way, or you want to repair the disk your Mac starts up from, open Disk Utility from macOS Recovery:
- Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:
- Apple silicon: Turn on your Mac and continue to press and hold the power button until you see the startup options window. Click the gear icon labeled Options, then click Continue.
- Intel processor: Turn on your Mac, then immediately press and hold these two keys until you see an Apple logo or other image: Command (⌘) and R.
- You may be asked to select a user you know the password for. Select the user, then click Next and enter their administrator password.
- From the utilities window in macOS Recovery, select Disk Utility and click Continue.
Select your disk in Disk Utility
Choose View > Show All Devices (if available) from the menu bar or toolbar in Disk Utility.
The sidebar in Disk Utility should now show each available disk or other storage device, beginning with your startup disk. And beneath each disk you should see any containers and volumes on that disk. Don't see your disk?
In this example, the startup disk (APPLE HDD) has one container and two volumes (Macintosh HD, Macintosh HD - Data). Your disk might not have a container, and it might have a different number of volumes.
Repair volumes, then containers, then disks
For each disk that you're repairing, start by selecting the last volume on that disk, then click the First Aid button or tab. Vital signs (jem smith, lolthersart) mac os.
In this example, the last volume on the disk is Macintosh HD - Data.
Click Run to begin checking the selected volume for errors.
- If there is no Run button, click the Repair Disk button instead.
- If the button is dimmed and you can't click it, skip this step for the disk, container, or volume you selected.
- If you're asked for a password to unlock the disk, enter your administrator password.
After Disk Utility is done checking the volume, select the next item above it in the sidebar, then run First Aid again. Keep moving up the list, running First Aid for each volume on the disk, then each container on the disk, then finally the disk itself.
In this example, the repair order is Macintosh HD - Data, then Macintosh HD, then Container disk3, then APPLE HDD.
If Disk Utility found errors that it can't repair
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If Disk Utility found errors that it could not repair, use Disk Utility to erase (format) your disk.
If your disk doesn't appear in Disk Utility
If Disk Utility can't see your disk, it also can't see any containers or volumes on that disk. In that case, follow these steps:
- Shut down your Mac, then unplug all nonessential devices from your Mac.
- If you're repairing an external drive, make sure that it's connected directly to your Mac using a cable that you know is good. Then turn the drive off and back on.
- If your disk still doesn't appear in Disk Utility, your Mac might need service. If you need help, please contact Apple Support.
