People use Quora to document the world around them. Over time, the database of knowledge should grow and grow until almost everything that anyone wants to know is available in the system. When knowledge is put into Quora, it is there forever to be shared with anyone in the future who is interested. Reusable
Each question page on Quora is a reusable resource that should help everyone who has the question that the page is about. Answers on question pages don't depend on any context about the asker except for what is specified in the question text and details. There is only one version of each distinct question on the site, so everyone who is interested in or knows about that material is focused on that one place. Collaborative
Almost any public space on Quora can be edited by anyone who knows how to improve it. This includes the text of questions and the details around them, what topics are attached to which questions, and the summaries of answers. Quora relies on the good faith of everyone using it to make it a high quality resource. Continually Improving
People can write their own answers to questions any time they think a question page could become a better resource with more information added to it. People who read question pages rate the different answers so that the best ones can rise to the top of the page and make it better. And people can comment on each other's answers to help them make those better as well.
What powered Quora? Please refer to http://www.quora.com/Why-did-Quora-choose-to-develop-in-Pylons
Tornado is used as Comet server.