Final answer:
The BIOS is essential for initializing a computer's hardware and setting up communication pathways for the operating system. You might change BIOS settings to modify the boot order when installing a new operating system from an external device, like a USB drive.
Step-by-step explanation:
The BIOS (Basic Input/Output System) is a crucial component on a computer as it performs the initial hardware checks and sets up the communication pathways that allow the operating system to interact with the CPU, memory, and other hardware. After powering on the computer, the BIOS identifies, tests, and initializes system devices such as the video display card, hard disk, USB devices, and other hardware. This process is known as the Power-On Self Test (POST).
One example of when you would change something in the BIOS is if you're adding a new piece of hardware that requires you to modify the boot order. For instance, if you're installing a new operating system from a USB flash drive, you may need to access the BIOS settings to change the boot order so the computer boots from the USB drive before the hard drive.