To make a bootable USB flash drive with Debian, perform several actions:
1) Download the image of Debian from the official site
https://www.debian.org/CD/
Old versions can be downloaded here
http://cdimage.debian.org/cdimage/archive/
2) Download “Universal USB Installer”
pendrivelinux.com/universal-usb-installer-easy-as-1-2-3/
files.ixnfo.com/Soft/Universal-USB-Installer-2.0.1.4.zip
3) We connect the USB flash drive to the computer and run the Universal USB Installer. In it, we agree with the license agreement by clicking “I Agree“, in the second window where “Step 1:” choose “Debian Live” or “Debian Netinst” depending on the downloaded image, where “Step 2” click “Browse” and point to the downloaded Debian image. In “Step 3:” select the letter of the flash drive, tick the “Format” (this will re-partition the file system table and erase all the data on the USB flash drive).
“Step 4:” you can not touch it if you only want to install Debian from the USB flash drive. If you change it (this will slightly prolong the process of creating a bootable USB flash drive), you can use the specified space on the USB flash drive to save user data, for example, if you boot from a USB flash drive and run Debian instead of installing it, all the settings made in the system will be saved to the USB flash drive (for example, bookmarks in the browser, installed components).
4) Click “Create” and we are waiting for the completion of the process.