What is Stack Exchange?

Stack Exchange is a growing network of individual communities, each dedicated to serving experts in a specific field. We build libraries of high-quality questions and answers, focused on each community's area of expertise.

From programmers sharing answers on parsing HTML, to researchers seeking solutions to combinatorial problems, to photographers exposing lighting techniques, our communities are built by and for those best able to define them: the experts and enthusiasts.


How does it work?

The sites are free and open to everyone – you can ask or answer questions without even bothering to register. Better yet, you have access to the full archive of existing questions and answers – again, without needing to give up so much as an email address.

Of course, all this information is worthless if you can't find the answer you need. So we empower our communities to curate it:

When someone asks a question on a Stack Exchange site, the community reviews, revises, and proposes answers to it.

Answers are rated and ranked by the rest of the community. Members also vote for questions they find useful, or against those they see as unclear or unproductive. The more votes, the more visibility – so when you search, you get the best answer to the best question.

Questions and answers can be edited by other members, Wikipedia-style. This lets the community continue to polish and update content even when the original authors aren't available.


What's special about Stack Exchange?

You wouldn't shout out a calculus question in a football stadium, right? You'd go to the math department of a university. That's why instead of allowing questions on any topic, we bring together individual communities of experts on very specific topics.

We welcome questions that are clear and specific, representing real problems that you face; Stack Exchange is not the place for conversation, opinions, or socializing.

We don't open a site until we're sure there's a critical mass of experts ready to participate. If you can't find a Stack Exchange site for your area of expertise, you can propose one on our Area 51 site – if enough of your peers sign on, we'll create it.

Stack Exchange's focus on professional communities and real-world problems results in over 80% of questions getting great answers, fast.


Where did Stack Exchange come from?

In 2008, Jeff Atwood and Joel Spolsky created a site called Stack Overflow and brought together millions of computer programmers from around the world to help each other with detailed technical questions. That site was a phenomenal success, so, after securing a $6 million investment from Union Square Ventures, they created the Stack Exchange Network and started launching new sites in August of 2010. There are now 118 separate sites and over 64 million monthly unique visitors (as of November, 2012) –and growing!