What does 'boot order' refer to?

'Boot order' specifically refers to the sequence in which a computer's BIOS or UEFI firmware checks various devices to find a valid operating system to load during the startup process. When you power on a computer, it does not automatically know where to look for the operating system; thus, it follows the predefined boot order that is set in the system's firmware settings.

This order can include various types of devices, such as hard drives, USB drives, optical drives, and network devices. The first device in this sequence that contains a bootable operating system is the one that will be used to load the OS, allowing the computer to start and become operational.

Understanding the boot order is essential, especially when troubleshooting boot issues, as misconfigurations can prevent a system from starting properly or can lead to booting from the wrong device.