Docker was developed inside dotCloud, a platform-as-a-service start-up, and shown publicly by Solomon Hykes at PyCon in March 2013. It packaged Linux kernel features such as namespaces and cgroups behind a simple CLI, Dockerfiles and an image registry. The company renamed itself Docker, Inc. and Docker became the standard way to ship applications.
Docker helped found the Open Container Initiative and donated containerd to the CNCF. Kubernetes now runs containerd directly rather than through Docker. Docker Engine remains open source under the Moby project, while Docker Desktop for Windows and macOS needs a paid subscription for larger companies.