Software & Apps Windows 147 147 people found this article helpful What Does Booting Mean? The boot process governs from power-on to operating-system loading by Tim Fisher General Manager, VP, Lifewire.com Tim Fisher has 30+ years' professional technology support experience. He writes troubleshooting content and is the General Manager of Lifewire. our editorial process Facebook Twitter LinkedIn Tim Fisher Updated on April 05, 2020 Windows The Ultimate Laptop Buying Guide Tweet Share Email The term boot describes 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. Windows XP Boot Process (into Safe Mode). Screenshot What Goes On During the Boot Process? When the power button turns 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 next step of the boot process is controlled by BIOS or EFI 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. VVadyab / Getty Images Hard (Cold) Booting Versus Soft (Warm) Booting 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. 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 Problems that occur during the boot process aren't common, but they do happen. See our article on how to fix a computer that won't start for help figuring out what's wrong.