Docker is an open-source project that pioners the usage of container technologies with LXC, the container runtime it was using at the time. Unlike virtual machines which emulate virtual hardwares, containers share the resources of the operating system and are much more efficient. Docker leverages Linux kernel features including cgroups and namespaces to isolate processes and ensure they run independently with the expected resources. Docker also smoothens the process for creating, building containers, sharing and versioning images.

Docker images are created from Dockerfile and are uploaded to online repositories like the Docker Hub in order to be shared publicly with the community or privately within your organization. By design Docker enforces modulatiry and allows developers to pack, ship and run any applications as a lightweight, portable and self-sufficient containers. By simplifying their usage and packing all the underlying technologies into a coherent product, Docker was the main driver towards the adoption of container technologies across the industry.