stackoverflow is the site to go to for answers to your technical questions related to programming. Actually it is getting so popular that you don’t need to visit it directly — it shows up in response to your search queries.
There is a lot more to stackoverflow than asking and answering questions. On many sites, when someone answers a question, you have no idea of the expertise or reputation of that person. On stackoverflow, registered users can earn reputation (15 points currently) by answering questions which are accepted. If you have lot of knowledge related to programming, you can show it off by answering questions, have them accepted, increase your reputation score and more importantly, help others.
So, in general when someone with high reputation answers your question, you can be reasonably confident that it will be an useful answer.
There are many other ways of increasing (or decreasing) your reputation (score):
As mentioned, if you answer a question that is accepted, you get 15 points. The acceptor gets 2 points.
- if someone thinks that your question is useful and clear, they can upvote it and you get 5 points.
- You get 10 points if someone upvotes your answer. That is, they think your answer is useful.
- Note that you need to have a minimum reputation of 15 before you can upvote
- if someone feels that your that question or answer is not useful or clear, they can downvote it and you lose 2 points.
- As with upvote, you need to have a minimum reputation of 125 before you can downvote. Not only is the minimum required reputation for downvoting much higher, the person downvoting will lose 1 point from his reputation score — karma if you will.
There are checks and daily caps on how much reputation you can gain and how many votes you can cast. The reputation algorithm gets tweaked to ensure that it works as intended. Earlier when a question was voted up, the author of the question got 10 points — now it is 5.
You get more and more privileges as your reputation score increases: you can vote up, flag as offensive, leave comments, vote down, close questions, edit other people’s posts etc.
If your question is not being answered, you can give away some of your reputation points as a bounty — an incentive so that it will be answered soon. The bountied question will be prominently visible. I don’t think this is a good idea as it can skew the reputation scores.
You can get more info on how stackoverflow works by going to meta stackoverflow. As mentioned there, Reputation is a rough measure of "How much the community trusts you", "Your communication skills" and "The quality and relevancy of your questions and answers"
If this was not enough, there are badges — bronze, silver, gold.
The concept and software behind stackoverflow can be used for other community driven Q&A sites. An example is the site for questions relating to wordpress blogging software. Others are Q&A site for English language enthusiasts and linguists, Photography, Mathematics, Gaming etc. etc.