Amazon has launched Askville, a free web-based service that enables users to ask and answer questions on any topic.

The knowledge-sharing site was originally launched as an invite-only beta last year but is now available for anyone to try. Google Answers, which shut down last year, offered the same kind of service but for a fee.

Askville hopes to compete with Yahoo Answers, which launched in December 2005. Once a question has been asked at Askville it’s more likely to be answered correctly if topics are added so it can be easily categorised, according to Amazon. Questions on any topic can be posed to Askville, which aims to be a form of community site allowing users to meet others with similar interests. It differs from Yahoo Answers as it also integrates experience points that are awarded when an answer is provided.

Experience points, which determine how knowledgeable a member is, can be earned or lost in a variety of topics. The site also uses a virtual currency called Quest Coins, which are designed as an incentive to answer questions and which visitors to Askville can use to participate in adventures when Amazon’s new site Questville, launches later this year. Asking a question will earn the user 1 point whereas providing an answer that receives a “Best Answer” rating earns the user 15 points.

On the Askville Blog, an Amazon spokesperson said they ultimately “want to empower the Askville community to take ownership of the topics, which includes editing topics, merging topics and deleting topics”.