Docker Hub is a cloud-based public registry service to host both public and private images, share them, and collaborate with others. It has integration with GitHub and Bitbucket, and can trigger automated builds.
To host your image in Docker Hub, you need to create your Docker ID. This gives you the ability to create any number of public repositories in Docker Hub.
Docker Hub also gives you one free private repository. If you need more than one private repository, you can upgrade to a paid plan. A repository can hold different versions of an image.