What is a DAG and Why is it Important?

[jasnonaz]

What's your key point?
This is an incredibly important concept that we frequently want to link to and don't have a dedicated post for already
Prior art:
Christine's excellent post on modular data modeling - hoping for something with a lot of the same insights as this but focused on a short explanation of what dags are and how they are used
Link to notes / outline / draft:
Google docs preferred, please set sharing to anyone with the link can view.

Estimated first draft date:
Leave blank if you already shared a draft above.

Any open questions / requests for help from the group?

[gwenwindflower]

i think this should be tackled as a glossary entry, closing for now but feel free to open as a fresh discussion if you disagree!