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Stack Overflow is a question and answer site for professional and enthusiast programmers. It is a privately held website, the flagship site of the Stack Exchange Network,[5][6][7] created in 2008 by Jeff Atwood and Joel Spolsky.[8][9] It features questions and answers on a wide range of topics in computer programming.[10][11][12] It was created to be a more open alternative to earlier question and answer sites such as Experts-Exchange. The name for the website was chosen by voting in April 2008 by readers of Coding Horror, Atwood's popular programming blog.[13]

Stack Overflow
Stack Overflow logo.svg
Stack Overflow homepage, Feb 2017.png
Screenshot of Stack Overflow in February 2017
Type of site
Knowledge market
Available inEnglish, Spanish, Russian, Portuguese, and Japanese
OwnerStack Exchange, Inc.
Created byJeff Atwood and Joel Spolsky
Alexa rankIncrease 37 (as of 10 November 2019)[1]
LaunchedSeptember 15, 2008; 11 years ago (2008-09-15)[4]
Current statusOnline
Content license
CC-BY-SA 4.0[3]
Written inC# [2]

The website serves as a platform for users to ask and answer questions, and, through membership and active participation, to vote questions and answers up or down and edit questions and answers in a fashion similar to a wiki or Reddit.[14] Users of Stack Overflow can earn reputation points and "badges"; for example, a person is awarded 10 reputation points for receiving an "up" vote on an answer given to a question and 5 points for the "up" vote of a question, and can receive badges for their valued contributions,[15] which represents a kind of gamification of the traditional Q&A site. Users unlock new privileges with an increase in reputation like the ability to vote, comment, and even edit other people's posts.[16] All user-generated content is licensed under a Creative Commons Attribute-ShareAlike license.[17]

Closing questions is a main differentiation from Yahoo! Answers and a way to prevent low quality questions.[18] The mechanism was overhauled in 2013; questions edited after being put "on hold" now appear in a review queue.[19] Jeff Atwood stated in 2010 that duplicate questions are not seen as a problem but rather they constitute an advantage if such additional questions drive extra traffic to the site by multiplying relevant keyword hits in search engines.[20]

As of January 2019 Stack Overflow has over 10 million registered users,[21] and it exceeded 16 million questions in mid 2018.[22] Based on the type of tags assigned to questions, the top eight most discussed topics on the site are: JavaScript, Java, C#, PHP, Android, Python, jQuery and HTML.[23]

Stack Overflow also has a Jobs section to assist developers in finding their next opportunity.[24] For employers, Stack Overflow provides tools to brand their business, advertise their openings on the site, and source candidates from Stack Overflow's database of developers who are open to being contacted.[25]


The website was created by Jeff Atwood and Joel Spolsky in 2008.[8] On 31 July 2008, Jeff Atwood sent out invitations encouraging his subscribers to take part in the private beta of the new website, limiting its use to those willing to test out the new software. On 15 September 2008 it was announced that the public beta version was in session and that the general public was now able to use it to seek assistance on programming related issues. The design of the Stack Overflow logo was decided by a voting process.[26]

On 3 May 2010, it was announced that Stack Overflow had raised $6 million in venture capital from a group of investors led by Union Square Ventures.[27]

Content criteriaEdit

Stack Overflow only accepts questions about programming that are tightly focused on a specific problem. Questions of a broader nature–or those inviting answers that are inherently a matter of opinion– are usually rejected by the site's users, and marked as closed. The sister site is intended to be a venue for broader queries, e.g. general questions about software development.

User suspensionEdit

In April 2009, Stack Exchange implemented a policy of "timed suspension",[28] in order to curtail users who either show "No effort to learn (the community rules) and improve over time" or engage in "disruptive behavior" and become a nuisance. The suspension is accompanied by temporarily setting the user's reputation score at '1' and a notation on the user's profile page indicating the suspension and remaining duration.

Security breachEdit

In early May 2019, an update was deployed to Stack Overflow's development version. It contained a bug which allowed an attacker to grant themselves privileges in accessing the production version of the site. Stack Overflow published on their blog that approximately 250 public network users were affected by this breach, which "could have returned IP address, names, or emails".[29]

Moderator removalEdit

On September 27, 2019, a moderator of multiple Stack Exchange sites was dismissed from her moderator position, allegedly connected to behavior associated with upcoming changes to the Code of Conduct (CoC) relating to gender pronouns.[30][31][32]. Many other moderators resigned or suspended moderator activity in response to the dismissal. The company responded with a poorly received (downvoted nearly 2,000 times) message,[33], followed by a less negatively received apology several days later.[34].


A 2013 study has found that 75 % of users only ask one question, 65 % only answer one question, and only 8 % of users answer more than 5 questions.[35] To empower a wider group of users to ask questions and then answer, Stack Overflow created a mentorship program resulting in users having a 50% increase in score on average.[36] As of 2011, 92 % of the questions were answered, in a median time of 11 minutes.[37] Since 2013, the Stack Exchange network software automatically deletes closed questions that meet certain criteria, including having no answers in a certain amount of time.[38]

As of August 2012, 443,000 of the 1.3M registered users had answered at least one question, and of those, approximately 6,000 (0.46 % of the total user count) had earned a reputation score greater than 5000.[39] Reputation can be gained fastest by answering questions related to tags with lower expertise density, doing so promptly (in particular being the first one to answer a question), being active during off-peak hours, and contributing to diverse areas.[39]

In 2016, 1.5 million posts were deleted, of which about 8 % were deleted by moderators.[40]


Stack Overflow is written in C#[2] using the ASP.NET MVC (Model-View-Controller) framework, and Microsoft SQL Server for the database[41] and the Dapper object-relational mapper used for data access.[42] Unregistered users have access to most of the site's functionality, while users who sign in can gain access to more functionality, such as asking or answering a question, establishing a profile and being able to earn reputation to allow functionality like editing questions and answers without peer review or voting to close a question.


Stack Overflow has received general praise for its architecture of handling questions and answers as they are regulated by the community.[43] Its success has often been attributed to self-regulation.[citation needed]

Stack Overflow has been criticized for the proliferation of poor programming and development practices, specifically by encouraging developers to prioritize basic functionality at the expense of other features like security. A study from the University of Maryland found that Android developers that used only Stack Overflow as their programming resource tended to write more insecure code than those who used only the official Android developer documentation from Google.[44]

The site's culture has also been criticized for being needlessly harsh, abrasive, and unfriendly,[45][46] something which has been recognized by several Stack Overflow employees.[47][48]

See alsoEdit


  1. ^ " Competitive Analysis, Marketing Mix and Traffic - Alexa". Retrieved 1 October 2019.
  2. ^ a b "Which tools and technologies are used to build the Stack Exchange Network?". Meta Stack Overflow. Stack Overflow.
  3. ^ "Stack Exchange and Stack Overflow have moved to CC BY-SA 4.0". Retrieved 2 October 2019.
  4. ^ Spolsky, Joel (15 September 2008). "Stack Overflow Launches". Joel on Software. Retrieved 7 July 2014.
  5. ^ Sewak, M.; et al. (18 May 2010). "Finding a Growth Business Model at Stack Overflow, Inc" (PDF). Stanford CasePublisher. Stanford University School of Engineering. Rev. 20 July 2010 (2010-204–1). 204-2010-1. Retrieved 23 May 2014.
  6. ^ a b Jeff Atwood (16 April 2008). "Introducing". Coding Horror. Retrieved 11 March 2009.
  7. ^ Jeff Atwood (10 September 2008). "None of Us is as Dumb as All of Us". Coding Horror. Retrieved 11 March 2009.
  8. ^ Alan Zeichick (15 April 2009). "Secrets of social site success". SD Times. Retrieved 16 April 2009.
  9. ^ "Spolsky's Software Q-and-A Site". Slashdot. 16 September 2008. Retrieved 23 May 2009.
  10. ^ Joel Spolsky (25 April 2009). "Google Tech Talks: Learning from". YouTube. Retrieved 23 May 2009.
  11. ^ Jeff Atwood (6 April 2008). "Help Name Our Website". Coding Horror. Retrieved 15 July 2014.
  12. ^ Jeff Atwood (21 September 2008). "The Gamification". Coding Horror Blog. Retrieved 24 January 2011.
  13. ^ "What is reputation? How do I earn (and lose) it?". Stack Overflow. Retrieved 14 August 2010.
  14. ^ "List of privileges".
  15. ^ "Case Studies/".
  16. ^ "Closing changes: on hold, unclear, too broad, opinion-based, off-topic reasons, bye-bye to Too Localized".
  17. ^ "The war of the closes".
  18. ^ "Dr. Strangedupe: Or, How I Learned to Stop Worrying And Love Duplication".
  19. ^ "All Sites". Stack Overflow. Retrieved 15 April 2014.
  20. ^ "10,000,000th question is here!". Stack Overflow. 21 August 2015. Retrieved 10 August 2016.
  21. ^ "Tags". Stack Overflow. Retrieved 9 December 2014.
  22. ^ "Developer Jobs, Programming Jobs & More – Stack Overflow". Retrieved 12 December 2016.
  23. ^ "Stack Overflow Business". Retrieved 12 December 2016.
  24. ^ "J.Atwood & J.Spolsky founding -- but we need a logo". 30 April 2008. Retrieved 23 May 2014.
  25. ^ Ha, Anthony (4 May 2010). "Stack Overflow raises $6M to take its Q&A model beyond programming". VentureBeat. Retrieved 23 May 2014. The money we've raised means that, for the next ($6m / monthly burn rate) months, we can take on new projects, hire new people, and build new expert Q&A sites on a wide variety of new topics. Instead of opening sites in exchange for money, we’re about to launch a new, democratic system where anyone can propose a Q&A site, and, if it gets a critical mass of interested people, we'll create it.
  26. ^ Atwood, Jeff (6 April 2009). "A Day in the Penalty Box". StackOverflow Blog. Retrieved 6 April 2009.
  27. ^ Cimpanu, Catalin. "Stack Overflow says hackers breached production systems". ZDNet. Retrieved 22 June 2019.
  28. ^ "Firing mods and forced relicensing: is Stack Exchange still interested in cooperating with the community?". Meta Stack Exchange. 29 September 2019. Retrieved 28 October 2019.
  29. ^ "Stack Overflow Inc., sinat chinam, and the goat for Azazel". Mi Yodeya Meta Stack Exchange. 29 September 2019. Retrieved 28 October 2019.
  30. ^ "The mod firing squad: Stack Exchange embroiled in 'he said, she said, they said' row". 1 October 2019.
  31. ^ An Update to our Community and an Apology
  32. ^ An apology to our community, and next steps
  33. ^ Wang, Shaowei; David Lo; Lingxiao Jiang (18–22 March 2013). "An Empirical Study on Developer Interactions in StackOverflow". Singapore Management University. Archived from the original (PDF) on 25 February 2014.
  34. ^ Ford, Denae; Lustig, Kristina; Banks, Jeremy; Parnin, Chris (2018). ""We Don'T Do That Here": How Collaborative Editing with Mentors Improves Engagement in Social Q&A Communities". Proceedings of the 2018 CHI Conference on Human Factors in Computing Systems. CHI '18. New York, NY, USA: ACM: 608:1–608:12. doi:10.1145/3173574.3174182. ISBN 9781450356206.
  35. ^ Mamykina, Lena; Bella Manoim; Manas Mittal; George Hripcsak; Björn Hartmann (2011). "Design lessons from the fastest q&a site in the west". CHI '11 Proceedings of the SIGCHI Conference on Human Factors in Computing Systems: 2857–2866. doi:10.1145/1978942.1979366. ISBN 9781450302289.
  36. ^ "Turbocharging the Roomba: solutions for premature deletion".
  37. ^ a b Bosu, Amiangshu; Christopher S. Corley; Dustin Heaton; Debarshi Chatterji; Jeffrey C. Carver; Nicholas A. Kraft (2013). "Building Reputation in StackOverflow: An Empirical Investigation" (PDF). Tuscaloosa, AL 35487-0290, USA: Department of Computer Science, The University of Alabama.
  38. ^ "What posts get deleted, and why?". Meta.StackOverflow. 3 January 2017.
  39. ^ Jeff Atwood (21 September 2008). "What Was Stack Overflow Built With?". Stack Overflow Blog. Retrieved 23 May 2009.
  40. ^ Sam Saffron (30 March 2011). "How I learned to stop worrying and write my own ORM". Retrieved 22 July 2014.
  41. ^ Anderson, Ashton; Huttenlocher, Daniel; Kleinberg, Jon; Luskovec, Jure (2012). "Discovering Value from Community Activity on Focused Question Answering Sites: A Case Study of Stack Overflow" (PDF). Cornell University.
  42. ^ Y. Acar, M. Backes, S. Fahl, D. Kim, M. L. Mazurek and C. Stransky, "You Get Where You're Looking for: The Impact of Information Sources on Code Security," 2016 IEEE Symposium on Security and Privacy (SP), San Jose, CA, 2016, pp. 289–305. doi: 10.1109/SP.2016.25
  43. ^ "Suffering on Stack Overflow". 19 April 2019. Retrieved 6 September 2019.
  44. ^ "Tired of Stack Overflow". 22 August 2019. Retrieved 6 September 2019.
  45. ^ "The Puppet Race". 23 March 2018. Retrieved 6 September 2019.
  46. ^ "What a very bad day at work taught me about building Stack Overflow's community". 18 July 2019. Retrieved 6 September 2019.

External linksEdit