What are Docker image “layers”?

Question

I am brand new to Docker and am trying to understand exactly what a Docker image is. Every single definition of a Docker image uses the term \"layer\", but does not

Answer 1

I think the official document gives a pretty detailed explanation: https://docs.docker.com/engine/userguide/storagedriver/imagesandcontainers/.

_{(source: docker.com)}

An image consists of many layers which usually are generated from Dockerfile, each line in Dockerfile will create a new layer, and the result is an image, which is denoted by the form repo:tag, like ubuntu:15.04.

For more information, please consider reading the official docs above.