What does 'docker pull' command do?

The 'docker pull' command is designed to fetch an image from a Docker registry, which can be either a public registry like Docker Hub or a private registry that you set up. When you execute this command, Docker contacts the specified registry, retrieves the image manifest, and downloads the image layers to your local system. This allows you to have the necessary software stacks and dependencies available for your containers.

The command is essential for ensuring that you can deploy applications using pre-built images or shared images that meet your project’s requirements. By pulling images from a registry, you simplify the process of setting up the environment needed for your applications.

The context surrounding the other options emphasizes that they relate to different Docker functionalities, not the fetching process that 'docker pull' describes. For instance, deleting a container or an image, updating containers, or removing images involves distinct commands and functionalities that do not correspond to the pull operation focused on image retrieval.