Docker is a platform for developing and running containers. A container is a software package that bundles all essential components (the code of your application, runtime, system tools, libraries, settings, and other dependencies) so that it can be run in any environment.
With Docker, you can easily create, run, manage, and share containers, both on your local machine and in the cloud. It is also possible to create containers without Docker, but Docker makes it much easier to create, deploy, and manage containers.