All you need to install any version of Raspberry Pi OS is the Imager tool, an SD card and reader, and around ten minutes.

The Raspberry Pi Imager makes this process a cakewalk Unlike the average PC, the Raspberry Pi doesn’t ship with a tweakable BIOS menu, and it's pre-configured to boot from the microSD card.

The firmware included with the Raspberry Pi 2 Model B version 1.2 introduced the possibility of booting from a USB device: before that, it was only possible to boot from an SD or microSD card.