You could learn the nitty-gritty by reading the Wikipedia article or get the gist by reading GitHub's explanation.
To put it simply this is an Identicon:
You can pass a string of characters to this application and it'll magically create one of these Identicons. The above example was designed by passing the string, "Hunter".
Make sure you have Elixir installed on your computer. Download the codebase and from the project directory...
1. Fire up the Elixir console:
iex -S mix
2. Make an Identicon:
Identicon.make('Some words here, maybe your name?')
The image file will be available in the assets/ directory.
:) Enjoy