With the Docker you can setup live server-like environments for local development of apps.

This enables running more apps on the same servers used before, and also makes the packaging and shipping of programs very easy. That makes it available to have as many as four-to-six times the number of server application instances as you can using Xen or KVM VMs on the same hardware. While hypervisors can use different operating systems or kernels, Containers use shared operating systems and that makes them much more efficient in system resource terms. Instead of the hardware being virtualized, containers work on top of a single Linux instance.

Other companies, like Parallels, Google, and Docker have been working on open-source projects as OpenVZ and LXC (Linux Containers) to ensure that containers work well and securely. Oracle Solaris developed similar concept called Zones. It allows users, to run the apps in a sandbox, thus separating them one from another. The FreeBSD Jail had access to the operating system kernel and to very limited set of other system resources. Whilst mostly used in the last few years, the idea and concept for Containers dates back to at least the year 2000 and FreeBSD Jails.

Nxfilter docker