VirtualBox is ridiculously simple to set up and get virtual machines going. Shared folders, shared clipboard and much more are no issue.
But.
It eats resources. The installed virtual machines (VM) run relatively slow. What have you found to be feature comparable - and most importantly more resource-efficient - alternatives for running VMs under Linux?
As jet points out, QEMU for actual hardware virtualisation.
There is one relevant thing, which is not exactly in the same category, but does somewhat similar thing:
containers
most popular example being Docker
https://en.wikipedia.org/wiki/Containerization_(computing)
containers don’t emulate whole hardware stack like virtual machines do, they just run the guest OS on top of host OS.
so because they don’t put resources towards emulating hardware, they are much more resource efficient.
so if your problem is “I’m running Fedora but I want to run something that for some reason runs just on Ubuntu”, then you could use containers for that.
containers are mostly used in headless environments (as in servers, no GUI), so running and displaying desktop Linux inside them is a bit tricky, but it can be done.
Containers don’t emulate anything. They have an OS installed within them. Typically you use Alpine Linux which super minimalistic and lightweight.
yes, valid point, thank you for the correction
for running GUI app, I use flatpak which is a sort of a container / sandbox