Rufus is a tool that helps to create bootable USB drives, such as USB keys, memory sticks, etc.
It can be particularly helpful in the following cases:
You need to create USB installation media from bootable ISOs (Windows, Linux, UEFI, etc.)
You need to work on a system that does not have an operating system installed
You need to flash a BIOS or firmware from DOS
You want to run a low-level program