Duolingo Wiki & FAQ (unofficial, but still amazing)
Where can I find a Duolingo FAQ? Check Duolingo's official Help Center (Duolingo Plus/
Purchases, Educators, Ambassadors, Report Bugs, and more!) If you don't find what you're looking for there, check out the these awesome Duolingo Wiki (etc.) guides:
The Wiki's unofficial Duolingo FAQ
Mod or No Mod Guide to Reporting Posts and Incidents
What are some common forum mistakes aka faux pas that I can avoid?
How to best utilize the Sentence Discussion forums
How to protect your streak beyond the basics of just equipping a streak freeze.
How to find popular posts without wading through as many sticky posts.
I want to create an XP competition, what should I know?
What does the inside of the Incubator look like?
All of this and more on the unofficial Duolingo Wiki.
(Suspended indefinitely while folks are unable to contact mods directly: Non-mods pointing out Guideline violations
Community Guidelines Clarification
The wiki too big? Getting lost? Just go to Google and type Duolingo Wikia and a search term such as Clubs, or Streak Freeze and find exactly what you're looking for. Or, use a key word in the Wiki's search bar.