[Docker](https://www.docker.com/) is a widely-used container platform available for Linux, Windows, and Mac, as well as cloud providers like AWS and Azure.
A common use case would be to package an app and all its requirements in a container. The container can then be used during development, passed to quality assurance/testing, and on to production/operations. This eliminates the "works on my machine" mentality, as the container effectively _is_ the machine, no matter what actual hardware it may be running on.