A partial glossary of terms used in this guide. For more complete descriptions of the components in JupyterHub, see Tools used in a JupyterHub Deployment. Here we try to keep the definition as succinct and relevant as possible, and provide links to learn more details.

admin user
A user who can access the JupyterHub admin panel. They can start/stop user pods, and potentially access their notebooks.
The way in which users are authenticated to log into JupyterHub. There are many authenticators available, like GitHub, Google, MediaWiki, Dummy (anyone can log in), etc.
A separate process that stops the user pods of users who have not been active in a configured interval.
docker image
A docker image is similar to a recipe that Docker can use to build a working space which gives users the tools, libraries, and capabilities to be productive.
environment variables
A set of named values that can affect the way running processes will behave on a computer. Some common examples are PATH, HOME, and EDITOR.
persistent storage
A filesystem attached to a user pod that allows the user to store notebooks and files that persist across multiple logins.
A tool which lets you quickly convert a GitHub repository into a Docker image that can be used as a base for your JupyterHub instance.