Groups are sorted by their main focus.
I have not included groups about deviantMEETs as there are too many groups. For those you should browse the groups page to find one about your area.
There is one group you should watch/join for sure if you want to keep up to date with deviantART related matters:
Official Groups
:icondevbug: :iconpremiummembers:
Community
Projects
CSS and Scripts
Profile / Account Customization
Stamps
Memes / Adoptables
News / Zines / Dictionaries / Tutorials
Mixed
If there is a group you think that is missing here, let me know about it!
Please do not suggest point-/llama-trading groups or anything similar. While they are kind of dA related, i don't support them and question their purpose. Thanks for your understanding.