Docker ( Docker ) is an open source community product that was selected as one of the “Open Source Rookie of the Year” annually by Black Duck Software, which verifies open source licenses in 2013.
Docker is an open-source container-based virtualization software used by PaaS vendor DotCloud as the backend of its PaaS.
What about Docker?
Until now, virtualization was known only as VirtualBox, KVM, and VMWare, but a completely new type of virtualization engine has appeared.

This new Docker is a lightweight and fast virtualization technology that allows you to start and use a large number of virtual machines on a system right away.

Technically, Docker is an economical virtualization engine for a new type of PaaS that combines LXC and AUFS to make it usable in the form of GitHub.
Docker is one of the Linux Containers (LXC)
Docker, simply put, is a wrapper around Linux Containers (LXC).

But it doesn’t just wrap LXC, it also uses the Docker Union filesystem to make container operations manageable changes with a familiar interface like commit or push .

LXC is a type of virtualization technology that allows virtual machines called containers to be used as independent host environments. Unlike Xen Server, which uses hypervisor-type virtualization technology, LXC is very lightweight and fast.
Sold Docker Enterprise business to DOCKER MIRANTIS
On November 13, 2019, Mirantis announced that it had acquired Docker’s Docker Enterprise business.
Docker, an American company that provides container technology Docker and commercial versions for enterprises, announced that it had agreed to sell the Docker Enterprise Platform business to Mirantis.

“Mirantis Kubernetes technology combined with the Docker Enterprise Platform brings simplicity and choice to enterprises looking to move to the cloud,” said Adrian Ronell, CEO and co-founder of Mirantis. It is a cloud-native player of significant size that can provide an unconstrained alternative.”