Knowledge: If you have a question on your program material or projects, you can post it in Knowledge to get answers from your peers and from Mentors. Please feel encouraged to answer others' questions there, too!
Slack: The Robotics Slack community is primarily a peer-driven community for robotics enthusiasts. Udacity staff members do participate in the community Slack and are occasionally available for questions, but Slack is not an official support channel. The Slack community invite link is robotics.udacity.com.