page_title: Repository page_description: Definition of an Repository page_keywords: containers, concepts, explanation, image, repository, container # Repository ## Introduction A repository is a set of images either on your local Docker server, or shared, by pushing it to a [*Registry*](/terms/registry/#registry-def) server. Images can be associated with a repository (or multiple) by giving them an image name using one of three different commands: 1. At build time (e.g., `sudo docker build -t IMAGENAME`), 2. When committing a container (e.g., `sudo docker commit CONTAINERID IMAGENAME`) or 3. When tagging an image id with an image name (e.g., `sudo docker tag IMAGEID IMAGENAME`). A Fully Qualified Image Name (FQIN) can be made up of 3 parts: `[registry_hostname[:port]/][user_name/](repository_name:version_tag)` `username` and `registry_hostname` default to an empty string. When `registry_hostname` is an empty string, then `docker push` will push to `index.docker.io:80`. If you create a new repository which you want to share, you will need to set at least the `user_name`, as the `default` blank `user_name` prefix is reserved for official Docker images. For more information see [*Working with Repositories*](/userguide/dockerrepos/#working-with-the-repository)