Quora - Quora is a place to gain and share knowledge. It's a platform to ask questions and connect with people who contribute unique insights and quality answers.
Reddit - Reddit gives you the best of the internet in one place. Get a constantly updating feed of breaking news, fun stories, pics, memes, and videos just for you.
Stack Overflow - Community-based Q&A part of the Stack Exchange platform.
What If HQ - What If? HQ is a website where people can be curious and ask questions. What If? HQ is where no question is a bad question and everyone can share what they know.
Question2Answer - A Q&A site helps an online community to share knowledge.
Stack Exchange - Stack Exchange is a fast-growing network of 84 [and counting] question and answer sites on diverse...