Can anyone help identify what this is?

[slash4x4]

Can anyone identify/help with this:

What do the boxed letters represent, what is this diagram known as and what is it used for?

Also what are the number and sequence of strings you will get from reading this diagram.

[Brian Bushnell]

That's known as an "Uninformative Diagram Full Of Jargon" or UDFOJ.

[Bukowski]

Looks like a simple de Bruijn graph

[slash4x4]

I believe you are correct, your awesome