"The Docker Engine uses Linux-specific kernel features, so to run it on OS X we need to use a lightweight virtual machine (vm).
You use the OS X Docker client to control the virtualized Docker Engine to build, run, and manage Docker containers.
To make this process easier, we've designed a helper application called Boot2Docker that installs the virtual machine and runs the Docker daemon."
https://docs.docker.com/installation/mac/
"The Docker Engine uses Linux-specific kernel features, so to run it on OS X we need to use a lightweight virtual machine (vm).
You use the OS X Docker client to control the virtualized Docker Engine to build, run, and manage Docker containers.
To make this process easier, we've designed a helper application called Boot2Docker that installs the virtual machine and runs the Docker daemon."
https://docs.docker.com/installation/mac/