In the common case:

Boot Ventoy application via GRUB/EFI

Ventoy EFI application scans the same drive it booted from with a vfat driver for disk images.

Ventoy then creates chainload grub commands for every image it finds.

You are presented a list of boot options, just like a normal grub boot.

Selecting an option chainloads a boot from that disk image.

There's devil in the details of course, but largely that's how it's working.

If you mean, technically, I can't help you.

But for users: You install Ventoy on your USB drive, and then you can drop ISO files in a folder. On startup, Ventoy opens and you can choose the ISO to boot.

This means you just have one bootable USB, and no more using tools to create bootable usb drives.

There is a "How Ventoy works" section.

First part is listing there open source dependencies

https://www.ventoy.net/en/doc_disk_layout.html

https://www.ventoy.net/en/doc_disk_layout_gpt.html

https://www.ventoy.net/en/doc_mbr_vs_gpt.html

...

See https://en.wikipedia.org/wiki/Ventoy#How_does_Ventoy_work, TLDR when you pick an ISO, it sets up a virtual device which emulates a regular bootable device, pointing to the contents in the ISO.

This section of the wikipedia article is entirely uncited, and reads vaguely like LLM output. Ventoy is not a hypervisor (afaik), so how does it present an emulated device to a chainloaded OS?

This is the edit that introduced that section, originally titled "How does Ventroy works" https://en.wikipedia.org/w/index.php?title=Ventoy&diff=12247...