The main functionality of the Docker registry is to find a certain image based on a description. The registry handles Docker Images in repositories. It's important to understand the difference between registry and repository. Docker registry is a service that is storing your Docker Images, and repository is a collection of different docker images with the same name, which have different tags (we will get back to tags in a while). Like the git counterpart, a Docker repository is identified by a URI and can either be public or private.
The most recognized hosted version of a Docker registry is the Docker Hub. It comes with a nice and usable UI. The Docker Hub is a software-as-a service (SaaS) platform for sharing and managing Docker images. In other words, it's a cloud-based registry service capable of hosting and distributing images. Images are being kept either in public or private repositories. Currently, the Hub serves hundreds of thousands public repositories and the number...