docker pull | Docker Documentation
https://docs.docker.com/engine/reference/commandline/pullDocker images can consist of multiple layers. In the example above, the image consists of two layers; fdd5d7827f33 and a3ed95caeb02. Layers can be reused by images. For example, the debian:jessie image shares both layers with debian:latest.Pulling the debian:jessie image therefore only pulls its metadata, but not its layers, because all layers are already present locally: