Well, since 2010 Sun has died, and opensolaris is no more. It lives on as an open source effort called Illumos. At one point, solaris could run Linux binaries unmodified under a solaris kernel and userspace. That became un-maintained, but it is now working again.

One of the reasons this feature fell out of use was because it could only run 32-bit linux binaries. Now it can run 64-bit binaries too.

If you want to try it out there is a company you may not be familiar with, dear time-traveler from 2010, called Joyent, that will let you use this.

What is very interesting dear time traveler is that there is a format for containing programs and their environments called docker that allows you to use features, as you could in a zone, but which is easier to use than zones. You can deploy your containers built on linux to solaris zones with this feature, and Joyent lets you do it.

I assume that the time traveller knows Open Solaris up to 2010.

Someone used Linux facilities that are somewhat similar to Solaris Zones and ZFS snapshots (you'll know those, since Solaris 10 from 2005 shipped with that and wasn't even the first) to build an ecosystem for lightweight virtual systems with standardized interfaces. That system is called Docker (and runs on Linux, obviously)

OpenSolaris is all but dead, but a community succeeded it, called IllumOS. People from that community decided to attempt to use Solaris Zones, with Linux branded zones (that capability was dropped in the meantime so they had to invest some effort to bring it up again) to reimplement Docker on an IllumOS (ie. OpenSolaris) foundation.

Love the question. This should be the new ELI5. I think a lot of articles on here would benefit from answering that question.

Remember when virtual machines came out? That technology gave us tools to create a 'layered' effect for compute related resources on a single, managed machine. Microservice technologies, like Docker containers, are a logical extension of that layering into the process space on the machine, and in many cases multiple virtual machines running on a single machine.

It's all about the layers, man.