What Does Booting Mean?

Screenshot of a Windows XP booting into Safe Mode

Tim Fisher

The term boot is used to describe the process taken by the computer when turned on that loads the operating system and prepares the system for use.

Booting, boot up, and start up are all synonymous terms and generally describe the long list of things that happen from the pressing of the power button to a fully-loaded and ready-to-use session of an operating system, like Windows.

What Goes On During the Boot Process?

From the very beginning, when the power button is pressed to turn the computer on, the power supply unit gives power to the motherboard and its components so that they can play their part in the whole system.

The first part of the next step of the boot process is controlled by BIOS and begins after the POST. This is when POST error messages are given if there's a problem with any of the hardware.

Following the display of various information on the monitor, like the BIOS manufacturer and RAM details, BIOS eventually hands the boot process over to the master boot code, that hands it to the volume boot code, and then finally to the boot manager to handle the rest.

This is how BIOS finds the right hard drive that has the operating system. It does this by checking the first sector of the hard drives it identifies. When it finds the right drive that has a boot loader, it loads that into memory so that the boot loader program can then load the operating system into memory, which is how you use the OS that's installed to the drive.

In newer versions of Windows, BOOTMGR is the boot manager that's used.

That boot process explanation you just read is a very simplistic version of what happens, but it gives you some idea of what's involved.

Hard (Cold) Booting Versus Soft (Warm) Booting

You may have heard the terms hard/cold booting and soft/warm booting and wondered what was meant. Isn't booting just booting? How can you have two different types?

A cold boot is when the computer starts up from a completely dead state where the components were previously without any power at all. A hard boot is also characterized by the computer performing a power-on self-test, or POST.

However, there are conflicting perspectives on what a cold boot really involves. For example, restarting a computer that's running Windows may make you think that it's performing a cold reboot because the system appears to turn off, but it may not actually shut down the power to the motherboard, in which case it would be applying a soft reboot.

Wikipedia has some more information on what various sources have to say about cold and warm booting.

Note: Hard reboot is also the term used to describe when the system isn't shut down in an orderly way. For example, holding down the power button to shut the system down for the purpose of restarting, is called a hard reboot.

More Information on Booting

You may think that learning about the boot process is silly or pointless and maybe it is for most people, but not always. If you want to learn how to boot the computer from a flash drive or disc, you have to first understand that there comes a point during the boot process that gives you that opportunity.

Problems that occur during the boot process aren't common, but they do happen. See how to fix a computer that won't start for help figuring out what's wrong.

The term "boot" comes from the phrase "pull oneself up by one's bootstraps." The idea is to understand that there must be a piece of software that can run initially, before other software, in order for the operating system and programs to be able to run.