Piazza is a free Q&A platform and is integrated in Canvas. With it, instructors are able to use the power of community to help students learn since it features a Wiki style format that enables collaboration in a single space. Instructors and students can add questions, posts or polls for the class to view and/or answer. Instructors can endorse high quality answers to keep the class on track and you can easily customize online polls to suit their needs.
Piazza can be added to any Canvas course site by enabling the tool in the course navigation.