Early versions of the Raspberry Pi could only boot from SD cards, but newer ones can boot from any USB device, like an external drive or USB stick. Here's how.

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.

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.

When it finishes, eject the SD card and re-insert it into your Raspberry Pi. When you boot it up, it should be in the exact same state it was in when you first cloned the SD card.

Power off your Raspberry Pi, remove the card from its slot, push it back in ensuring it's completely installed, and power the device back on. Alternatively, you may have a low-quality SD card.

For the Raspberry Pi 1, 2, Compute Module, and Zero, there are two boot modes – SD boot, and USB Device boot, with USB Device boot only found on the Compute Module.