A boot causes the computer to start executing instructions. PCs and Macs contain built-in instructions in a ROM or flash memory chip that are automatically executed on startup. These instructions search for the operating system, load it and pass control to it. Booting a computer today means turning it on or selecting Restart. In the early days of computing, booting required pressing several buttons at the console.
Put Your Boots On!
The term comes from "bootstrap." Since bootstraps help you get your boots on, booting the computer helps it get its first instructions. The term is often used erroneously for application software. For example, you might hear someone say "let's boot Excel," whereas the correct usage is "launch Excel" or "load Excel." See
cold boot,
warm boot,
clean boot,
boot loader and
first boot sequence.
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All the Boots You'll Ever Need
System Commander was an earlier boot manager that allowed users to install any number of different operating systems on their PCs. On startup, this menu let you choose your OS. (Screenshot courtesy of V Communications, Inc.)