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.

USB boot has been possible since the Raspberry Pi 2 Model B (v1.2), but it has only become really worthwhile with the Pi 4. Here is some information, tips, tricks and opinions explaining why and how.

You can now boot the Raspberry Pi 3 from just about anything. The documentation for these new boot modes goes over the process of how to put an image on a USB thumb drive.

Historically, booting a Raspberry Pi required an SD card. However, if you follow [tynick’s] instructions, you can get a Pi 4 to boot from the USB port. Combine it with a small solid state disk ...

Explore the new Raspberry Pi boot menu, a game-changer for device flexibility, allowing easy boot from USB, NVMe, and network sources.

Raspberry Pi Foundation is almost ready to deliver a fix for Raspberry Pi 4's lack of support for USB mass storage boot.

And, as you're going to be installing and using Linux on your Raspberry Pi, it makes good sense to create your SD card from within a Linux environment.

This means the Raspberry Pi 3 can boot from a flash drive or a USB hard drive instead of a SD card.