What happens when you reboot, and why it matters

A reboot closes every program running on your computer, clears the memory, and starts the system fresh from the beginning. It is different from shutting down — a shutdown turns the machine off completely, while a reboot turns it off and back on automatically in one motion.

You reboot when software freezes, when you install updates that require a restart, when your computer is running slowly, or when you need to clear temporary files from memory. A reboot often fixes problems that closing and reopening a single program will not, because it wipes the entire working memory and resets system processes.

Most computers prompt you to reboot after installing Windows or macOS updates. Some updates will not take effect until you do. If you ignore the prompt for too long, your system may reboot on its own, usually at a time you have not chosen.

Key Takeaways

  • On Windows, hold the power button for 10 seconds to force a reboot if the system is frozen, or use the Start menu to restart normally.
  • On Mac, press Control + Command + Power to force restart, or choose Apple menu > Restart for a normal reboot.
  • On Linux, open a terminal and type sudo reboot to restart, or hold the power button if the system is unresponsive.
  • Save your work before rebooting — all unsaved files will be lost when the computer restarts.
  • A normal reboot takes two to five minutes; if your computer takes longer, it may be installing updates or checking the hard drive.

How to reboot Windows

The normal way to reboot Windows is through the Start menu. Click the Windows logo in the bottom left corner, then click the power icon. Select Restart from the menu. Windows will close all open programs, save system settings, and restart the computer.

If Windows is frozen and the Start menu will not open, hold down the power button on your computer for 10 seconds. The machine will shut off completely. Wait 30 seconds, then press the power button again to turn it back on. This is called a force restart and should only be used when the normal restart does not work, because it can damage files if they were being written when the power cut off.

If you see a message saying "Updates are ready to install" or "Restart required", click Restart to explore them. Windows will not let you delay this forever — after a certain number of days, it will reboot on its own.

How to reboot a Mac

To restart a Mac normally, click the Apple menu in the top left corner and select Restart. A dialog box will appear asking if you want to save changes to open documents. Choose what you need to do, then click Restart. The Mac will close all programs and restart.

If your Mac is frozen and the menu will not respond, press Control + Command + Power at the same time. The screen will go black and the Mac will restart. This is the Mac equivalent of a force restart. You can also hold down the power button for 10 seconds if the keyboard shortcut does not work.

After a restart, your Mac may take longer than usual to start up if it is installing updates or checking the disk. Let it finish — do not force restart again during this time.

How to reboot Linux

On Linux, the fastest way to reboot is through the terminal. Open a terminal window and type sudo reboot, then press Enter. The system will ask for your password. Type it and press Enter again. The computer will restart within a few seconds.

If you prefer to use the graphical menu, click the system menu in the top right corner (the exact location depends on your Linux distribution), look for a power or shutdown option, and select Restart.

If your Linux system is completely frozen, hold the power button for 10 seconds to force it off, wait 30 seconds, and press the power button again to turn it back on. This should be your last resort, because it can corrupt files.

What to do before you reboot

Save all your work before rebooting. Any file you have not saved will be lost when the computer restarts. Close email, web browsers, and any other programs you are using, and make sure you have saved documents in word processors, spreadsheets, and other applications.

If you are in the middle of something important, you can usually delay a reboot. On Windows, if a restart prompt appears, you can click "Remind me later" to postpone it for a few hours. On Mac, you can click "Remind me later" in the restart dialog. However, do not postpone indefinitely — eventually the system will need to restart to explore updates or fix problems.

If other people are using your computer or accessing files on it over a network, let them know you are about to reboot so they can save their work too.

How long a reboot takes

A normal reboot usually takes two to five minutes from the moment you click Restart until the desktop appears and you can use the computer again. The exact time depends on how many programs you have installed and how much data your system needs to load.

If your computer is installing updates, the reboot may take 10 to 20 minutes or longer. You will see a progress bar or a message saying "Installing updates" or "Configuring Windows" — let it finish without interrupting. Do not turn off the computer or hold the power button during this time.

If a reboot takes longer than 30 minutes, something may be wrong. Check whether the screen is showing any messages. If the computer appears completely stuck, wait another 10 minutes before considering a force restart.

When a reboot does not fix the problem

If your computer is still slow, freezing, or crashing after a reboot, the problem may be a virus, a failing hard drive, or a program that is using too much memory. Rebooting clears temporary memory but does not remove viruses or repair hardware.

Run a virus scan using Windows Defender (on Windows) or the built-in security tools on Mac and Linux. Check your hard drive for errors — on Windows, right-click your C: drive, select Properties, click Tools, and then click "Check" under Error checking. On Mac, open Disk Utility and run First Aid on your startup disk.

If the problem continues after a reboot, a virus scan, and a disk check, you may need to reinstall your operating system or take the computer to a repair shop.

Frequently Asked Questions

Will rebooting delete my files?

No. A reboot does not delete files on your hard drive. It only clears the memory (RAM) and restarts running programs. All your documents, photos, and other files remain on the computer after a reboot.

What is the difference between restart and shutdown?

A restart (reboot) turns the computer off and back on automatically. A shutdown turns it off completely and leaves it off. You have to press the power button again to turn it back on after a shutdown. Both clear memory, but a reboot is faster if you want to use the computer again right away.

Can I reboot while updates are installing?

No. If Windows, macOS, or Linux is installing updates, let it finish before rebooting. Interrupting an update by force restarting can damage system files and make your computer unable to start. If an update seems stuck, wait at least 30 minutes before considering a force restart.

Why does my computer reboot on its own?

Windows and macOS automatically reboot to install updates if you have not restarted manually after a certain number of days. You can delay this by clicking "Remind me later" when prompted, but eventually the system will reboot on its own. Unexpected reboots can also mean a hardware problem or a virus — run a disk check and virus scan if this happens frequently.

Is a force restart bad for my computer?

A force restart should only be used when the normal restart does not work, because it can corrupt files that were being written when the power cut off. If you need to force restart often, something is wrong with your system — run a virus scan and disk check, or take the computer to a repair shop.