netboot.xyz is a way to select various operating system installers or utilities from one place within the BIOS without the need of having to go retrieve the media to run the tool. iPXE is used to provide a user friendly menu from within the BIOS that lets you easily choose the OS you want along with any specific types of versions or bootable flags.

You can remote attach the ISO to servers, set it up as a rescue option in Grub, or even set up your home network to boot to it by default so that it's always available

For decades, the C and C++ standards treated multi-threading and concurrency as something existing outside the standard sphere - in that "target-dependent" world of shades which the "abstract machine" targeted by the standards doesn't cover. The immediate, cold-blooded replies of "C++ doesn't know what a thread is" in mountains of mailing list and newsgroup questions dealing with parallelism will forever serve as a reminder of this past.