An open-source tool to build and manage containers.

Docker allows you to create virtualized sandboxes to run and deploy software called containers. Docker can create and use images pulled from a container registry to build the environment for code, libraries, system settings, and more. Docker containers are flexible enough to run services in their own separate environments or wrap entire applications and their dependencies in virtualized and shareable containers. Use Docker to explore ready-to-go containers for popular applications without worrying about dependencies.

More info:

https://www.docker.com/
https://docs.docker.com/compose/