On the fourth day of Christmas, my true blog gave to me… Four Community Sites!

.. three Maturity Models, two Sitecore PaaS features, and Sitecore in a NuGet feed.

Community Docs

Built by the community, this documentation covers everything from MVC to xDB to SPEAK:

https://sitecore-community.github.io/docs/

Sitecore Community Forums

Built by Sitecore, powered by Telligent, these forums have gamification achievements built-in and the Sitecore product team monitors these forums, as well as the community itself. Great place to get some help when things aren’t a simple “Q&A”:

https://community.sitecore.net/

Sitecore Slack

Initially orchestrated in 2015, this community has grown over the last year into an amazing channel-based chat tool with over 1500 members sharing and helping each other out.

https://sitecorechat.slack.com

Sitecore Stack Exchange

Possibly the most impressive thing to come from the community this year was the creation of the Sitecore Stack Exchange. Thanks to a few key community members who drove the rapid rise of the community through Private Beta, the site is now in Public Beta. Anybody familiar with Stack Overflow or the rest of the Stack Exchange network will recognize the Q&A format.

http://sitecore.stackexchange.com/

*BONUS:* A Sitecore Stack Exchange post on ways to interact with the Community:

http://sitecore.stackexchange.com/questions/1689/how-can-i-connect-with-the-sitecore-community