Most well-known question-and-answer Website on the Internet

Quora.com is one of the most well-known question-and-answer websites on the Internet.  It's free to use, and is somewhat more professionally-moderated than some of its competitors.  You can find questions and answers similar to the ones that you're looking for, or if you can't find them, you can ask a unique question yourself.  You can also answer questions posed by others, if you know how, and show off your expertise in various areas so that people will know what to ask you about.  You can also add to questions and answers, or debate which answer is the most correct.  Quora's main drawbacks are its somewhat complicated user interface (and lack of guidance for using it), as well as the fact that it's still mainly a community-driven website, so not every answer will be useful or completely correct.

If you're looking for other popular sites like Quora that allow you to hunt for answers to questions, pose questions that haven't already been answered, or help other people out by answering their questions for them, here are three that get mentioned frequently.

1. Yahoo Answers

(answers.yahoo.com)

Yahoo Answers is one of the most popular Quora alternatives.  It's free to sign up for, and includes a sort of "game" system where you gain points for answering other people's questions.  This increases the number of questions that you can ask or answer per day.  Though popular, it has been noted that Yahoo Answers isn't quite as professional or heavily-moderated as Quora.  This means that certain questions may be poorly formed or trivial, and answers may not necessarily correct.  Compounding this is that there is often a limited amount of time to answer a question or pick the "best answer", as opposed to on Quora, where debate can continue on a question and its answers indefinitely.

2. Fluther

(www.fluther.com)

Another often-cited alternative to Quora, Fluther's signature feature is that it has two main parts: "General" and "Social".  The "General" section is for questions that are asked with the intent of gaining knowledge on a topic, or sparking a thoughtful philosophical discussion.  The "Social" section is for questions that are more open-ended, meant to elicit opinions or a vote on popularity.  Whatever type of question you choose to ask (or answer), Fluther is free to use, and is a little more heavily moderated for quality than Quora or Yahoo Answers.

3. StackExchange

(www.stackexchange.com)

Originally conceived as a forum in which to ask and answer questions about computer programming, StackExchange has now become its own general question-and-answer network.  We say "network" because it organizes the questions that it receives into one of over 150 sub-websites based on their topics; for example, it has different sub-websites for questions on computer programming, computer specifications, games, mathematics, the English language, Apple computer products, and more!  Like on Quora, there can be more than one answer to a question, and users can vote on the best one.  Also, similar to Yahoo Answers, users can earn reputation points by asking, answering, or commenting on questions, or voting for best answers.  This expands their privileges on the site.