Downloading Debian
This is Debian 12, codenamed bookworm, netinst, for 64-bit PC (amd64) debian-12.8.0-amd64-netinst.iso.
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Debian installer ISOs are hybrid images, which means they can be written directly to CD/DVD/BD media OR to USB sticks.
Other Installers
Other installers and images, such as live systems, offline installers for systems without a network connection, installers for other CPU architectures, or cloud instances, can be found at Getting Debian.