Containers in the past were quite difficult to manage and use. Docker is basically a set of technologies to help us prepare, manage, and execute containers. In the world of virtual machines, we need a hypervisor to take care of all VM instances. Similarly, in the world of containers, we use Docker as the container engine to take care of everything to do with containers.

Undeniably, Docker is the most popular container engine to date. When using Docker, we follow the three concepts build, ship, and run, recommended by Docker itself:

• The workflow of Build-Ship-Run is optimized by the philosophy of Docker. In the Build step, we are allowed to build and destroy container images rapidly. As developers, we can include the container building steps as a part of our development cycle.
• In the Ship step, we ship container images to places, from our development laptops to the QA servers and to the staging servers. We send the container images to be stored in the public hub or to our private registry hub inside our company. Ultimately, we send our container images to run in the production environment.
• In the Run step, Docker helps us prepare the production environment with Swarm clusters. We start containers from the container images. We may schedule containers to run at a specific part of the cluster with a certain set of constraints. We manage a container's life cycle using Docker commands: