Before we start creating our own Docker images, let's take a moment exploring what images already exist? After all our goal is to solve problems not just to create random Docker images, so if there is already one that serves our purposes then it is better to use that.

Moreover, every Docker image we are going to build is going to be based on an already existing image.

If you visit the Docker hub and start searching you'll see there are tons of low-level images that provide the basics of one of the Linux distributions. For example, search for Ubuntu and you'll see there is an official Ubuntu image.

There are also application level images, for example there are imagaes for Wordpress and there are images that already include a certain Database (e.g. PostgreSQL) and other images that contain a programming language. For example Python.

In addition you can find the source of all the official images in A GitHub repository. Once you get familiar with the basics of Docker, it might be useful to review them.