Quora is an online question and answer community, it's sort of like a social media knowledge base with the base built by the members. It's easy to sign and it's free. Most people sign up via their Google, Facebook or Twitter accounts, although you can just use your email. People ask questions about all walks of life and people with the relevant experience answer them.

Good question, like Wikipedia it's only as good as the answers people give. To be fair there is a good level of authority in Quora although marketers have latched on and are starting to use it. But, there is a voting system and the better answers tend to rise to the top. The maxim is give true value and you'll get value. And like all algorithmic things, Quora try to get the cream to the top.

You can! If you answer questions based around relevant keywords you can add backlinks to your website. Atr the time of writing (May 2020) Quora has a Trust Flow of 44 so a backlink from that sort of site is definitely worthwhile.