Q4. What is Docker image?

Docker image is the source of Docker container. In other words, Docker images are used
to create containers. Images are created with the build command, and they’ll produce a
container when started with run. Images are stored in a Docker registry such as
registry.hub.docker.com because they can become quite large, images are designed to
be composed of layers of other images, allowing a minimal amount of data to be sent
when transferring images over the network.