Quora

Quora is a website for asking questions and posting answers. The company was launched in 2009 and the website opened in 2010.
Quora was founded by Adam D'Angelo and Charlie Cheever, both of them work for Facebook.
Making a Quora account is free and asking questions are free as well. Quora does not pay anyone for answering the questions asked by other users.
Quora has a Upvote/Downvote system. If you like an answer, you can upvote it and if you do not like it you can downvote it. Any user can upvote or downvote a question' answer no matter whether he asked that question or not. Quora has some strict policies to fight with spam and people posting copied content. If you do not follow them, your account will be suspended by the Quora Moderation team.