An open source OS virtualization system for all major Linux versions and Windows. As in regular computing, the OS is shared, but each application resides in its own "container" along with any required system tools and libraries. Docker was introduced in 2013 and quickly became popular as a way to deploy applications with less overhead and higher app density per server than using virtual machines (VMs). Numerous third-party products are available for Docker. See OS virtualization
, virtual machine
and Docker Hub
Docker vs. Virtual Machines
Standard server virtualization requires a guest OS in each VM, whereas Docker containers use the same OS kernel and save RAM space and overhead. The Docker Engine is used to manage the containers.