![SuperUser2](https://upload.wikimedia.org/wikipedia/commons/4/4c/SuperUser2.png)
Stack Exchange is a network of
question-and-answer (Q&A) websites
A website (also written as a web site) is a collection of web pages and related content that is identified by a common domain name and published on at least one web server. Examples of notable websites are Google, Facebook, Amazon, and Wiki ...
on topics in diverse fields, each site covering a specific topic, where questions, answers, and users are subject to a reputation award process. The
reputation system
Reputation systems are programs or algorithms that allow users to rate each other in online communities in order to build trust through reputation. Some common uses of these systems can be found on E-commerce websites such as eBay, Amazon.com, ...
allows the sites to be self-moderating. As of August 2019, the three most actively-viewed sites in the network are
Stack Overflow
In software, a stack overflow occurs if the call stack pointer exceeds the stack bound. The call stack may consist of a limited amount of address space, often determined at the start of the program. The size of the call stack depends on many facto ...
, Super User, and
Ask Ubuntu
Ask Ubuntu is a community-driven question and answer website for the Ubuntu operating system. It is part of the Stack Exchange Network, running the same software as Stack Overflow.
Members gain reputation based on the community's response (throu ...
.
All sites in the network are modeled after the initial site Stack Overflow, a Q&A site for
computer programming
Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as anal ...
questions created by
Jeff Atwood
Jeff Atwood (1970) is an American software developer, author, blogger, and entrepreneur. He co-founded the computer programming question-and-answer website Stack Overflow and co-founded Stack Exchange, which extends Stack Overflow's question-a ...
and
Joel Spolsky
Avram Joel Spolsky (born 1965) is a software engineer and writer. He is the author of ''Joel on Software'', a blog on software development, and the creator of the project management software Trello. He was a Program Manager on the Microsoft Exce ...
. Further Q&A sites in the network are established, defined and eventually if found relevant brought to creation by registered users through a special site named Area 51.
User contributions since May 2, 2018 are licensed under
Creative Commons Attribution-ShareAlike 4.0 International. Older content, contributed while the site used the
Creative Commons Attribution-ShareAlike 3.0 Unported license or the earlier Creative Commons Attribution-ShareAlike 2.5 Unported license, remains licensed under the license in force at the time it was contributed.
In June 2021,
Prosus
Prosus N.V., or Prosus, is a global investment group that is investing and operating across sectors and markets with long-term growth potential. It is among the largest technology investors in the world.
Prosus has invested across multiple verti ...
acquired Stack Overflow for $1.8 billion, which was the first complete acquisition of Prosus in
educational technology.
History
Foundation and growth
In 2008, Jeff Atwood and Joel Spolsky created Stack Overflow, a question-and-answer web site for
computer programming
Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as anal ...
questions, which they described as an alternative to the programmer forum
Experts-Exchange.
In 2009, they started additional sites based on the Stack Overflow model: Server Fault for questions related to
system administration and Super User for questions from computer
power user
A power user is a user of computers, software and other electronic devices, who uses advanced features of computer hardware, operating systems, programs, or websites which are not used by the average user. A power user might not have extensive tec ...
s.
In September 2009, Spolsky's company,
Fog Creek Software
Glitch (previously known as Fog Creek Software) is a software company specializing in project management tools. Its products include project management and content management, and code review tools.
History
Based in New York City, Fog Creek wa ...
, released a
beta version of the Stack Exchange 1.0 platform
as a way for third parties to create their own communities based on the software behind Stack Overflow, with monthly fees.
This
white label service was not successful, with few customers and slow growing communities.
In May 2010, Stack Overflow (as its own new company) raised US$6 million in
venture capital
Venture capital (often abbreviated as VC) is a form of private equity financing that is provided by venture capital firms or funds to start-up company, startups, early-stage, and emerging companies that have been deemed to have high growth poten ...
from
Union Square Ventures
Union Square Ventures (USV) is an American venture capital firm based in New York City. The firm has backed more than 130 startups, including Twitter, Etsy, Stripe, Coinbase, Zynga, Tumblr, Stack Overflow, Meetup, Kickstarter, MongoDB, Flur ...
and other investors, and it switched its focus to developing new sites for answering questions on specific subjects,
Stack Exchange 2.0. Users vote on new site topics in a staging area called Area 51, where algorithms determine which suggested site topics have
critical mass
In nuclear engineering, a critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. The critical mass of a fissionable material depends upon its nuclear properties (specifically, its nuclear fi ...
and should be created.
In November 2010, Stack Exchange site topics in
"beta testing" included physics, mathematics, and writing.
Stack Exchange publicly launched in January 2011 with 33 Web sites; it had 27 employees and 1.5 million users at the time, and it included advertising.
At that time, it was compared to
Quora
Quora () is a social question-and-answer website based in Mountain View, California. It was founded on June 25, 2009, and made available to the public on June 21, 2010. Users can collaborate by editing questions and commenting on answers that ...
, founded in 2009, which similarly specializes in expert answers.
Other competing sites include
WikiAnswers
Answers.com, formerly known as WikiAnswers, is an Internet-based knowledge exchange. The Answers.com domain name was purchased by entrepreneurs Bill Gross and Henrik Jones at idealab in 1996. The domain name was acquired by NetShepard and sub ...
and
Yahoo! Answers
Yahoo! Answers was a community-driven question-and-answer (Q&A) website or knowledge market owned by Yahoo! where users would ask questions and answer those submitted by others, and upvote them to increase their visibility. Questions were org ...
.
In February 2011, Stack Overflow released an associated job board called Careers 2.0, charging fees to recruiters for access, which later re-branded to Stack Overflow Careers.
In March 2011, Stack Overflow raised US$12 million in additional venture funding, and the company renamed itself to Stack Exchange, Inc. It is based in
Manhattan
Manhattan (), known regionally as the City, is the most densely populated and geographically smallest of the five boroughs of New York City. The borough is also coextensive with New York County, one of the original counties of the U.S. state ...
,
New York City
New York, often called New York City or NYC, is the most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the most densely populated major city in the Un ...
. In February 2012, Atwood left the company.
On April 18, 2013
CipherCloud
CipherCloud is an American software company providing cloud security to businesses. The company was established in 2010 and is based out of San Jose, California.
History
CipherCloud was founded in 2010 by Pravin Kothari, who previously co-founde ...
issued
Digital Millennium Copyright Act
The Digital Millennium Copyright Act (DMCA) is a 1998 United States copyright law that implements two 1996 treaties of the World Intellectual Property Organization (WIPO). It criminalizes production and dissemination of technology, devices, or ...
(DMCA) takedown notices in an attempt to block discussion of possible weaknesses of their encryption algorithm. The Stack Exchange Crypto group discussion on the algorithm was censored, but it was later restored without pictures.
, "Stack Exchange" no longer refers to the company, only the network of question-and-answer websites. Instead, the company is now referred to as Stack Overflow.
In 2016, Stack Exchange added a variety of new sites which pushed the boundaries of the typical question-and-answer site.
For example, Puzzling offers a platform for users who already know the answer to questions to challenge their peers to solve the problems unlike traditional Q–A sites where the poster does not know the answer.
Declining relationship between users and company
In 2016, Stack Exchange announced the second iteration of the Stack Exchange Quality Project, in which they attempt to implement specific important features requested by the community to meet a distinct high-priority set of goals. After users enthusiastically responded with feature ideas, they complained that there was insufficient action on the company's part.
In October 2018, the company removed its Interpersonal Skills site from the Hot Network Questions list after a complaint on Twitter, and an employee (who was part of the
SRE team, which was not community-facing) posted tweets attacking moderators.
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
Personal pronouns are pronouns that are associated primarily with a particular grammatical person – first person (as ''I''), second person (as ''you''), or third person (as ''he'', ''she'', ''it'', ''they''). Personal pronouns may also take di ...
. Many other moderators resigned or suspended their moderator activity in response to the dismissal. The company responded with two very-poorly-received messages which have since been deleted, and by a slightly less negatively-received apology several days later. In December 2019, the company posted a message, stating that they and the moderator had come to an agreement and expressing regret for any damage to her reputation. Nevertheless, this, plus the sudden departure of multiple community managers (Stack Exchange employees who interact with the community), led to an erosion of trust between the community and the company — convincing many of the site's most prolific users, including many community-elected moderators and a community manager, to depart within the next few months.
2019–2020 licensing change announcements
On September 2, 2019, the terms of service (and the footer of every page served) changed to referencing the "Creative Commons Attribution-ShareAlike" (CC BY-SA) license's 4.0 version instead of its 3.0 version.
Users were puzzled as to how Stack Overflow acquired the rights for this relicensing of their past contributions, with some users explicitly stating that they did not intend their contributions to be licensed under CC BY-SA 4.0. Users were concerned that, if the relicensing was found to be a breach of CC BY-SA 3.0, Stack Exchange would have made itself unable to distribute the content under any CC BY-SA license (and that the footer's license statement could be erroneous), and would have to rely on its "perpetual and irrevocable right and license to use, copy, cache, publish, display, distribute, modify, create derivative works and store" the content instead. On September 27, an official Stack Exchange reply stated it had been an "important step", but declined to discuss with the community the legal basis for the relicensing.
In March 2020, a post announced that content contributed before May 2, 2018 was available under a CC BY-SA 3.0 licence.
In the ensuing discussion, several users asked about the similar situation in August 2010, when Stack Exchange switched from accepting CC BY-SA 2.5 contributions to 3.0. A representative of the corporation noted "we are looking
..to show v2.5 for posts predating this change but cannot commit to it yet". Some users were unconvinced that the September 2019 announcement wasn't a breach of CC BY-SA 3.0 that would have caused its termination, and some answers weren't placated by the dateline chosen. In the ensuing discussion, Stack Overflow staff declined to comment.
Site features
Reputation and badges
The primary purpose of each Stack Exchange site is to enable users to post questions and answer them.
Users can vote on both answers and questions, and through this process users earn reputation points, a form of
gamification
Gamification is the strategic attempt to enhance systems, services, organizations, and activities by creating similar experiences to those experienced when playing games in order to motivate and engage users. This is generally accomplished thro ...
.
This voting system was compared to
Digg
Digg, stylized in lowercase as digg, is an American news aggregator with a curated front page, aiming to select stories specifically for the Internet audience such as science, trending political issues, and viral Internet issues. It was launch ...
when the Stack Exchange platform was first released.
Users receive privileges by collecting reputation points, ranging from the ability to vote and comment on questions and answers to the ability to moderate many aspects of the site.
Due to the prominence of Stack Exchange profiles in web search results and the Stack Overflow Careers job board, users may have reason to
game the system
Gaming the system (also rigging, abusing, cheating, milking, playing, working, or breaking the system, or gaming or bending the rules) can be defined as using the rules and procedures meant to protect a system to, instead, manipulate the system ...
.
Along with posting questions and answers, users can add comments to them and edit text written by others. Each Stack Exchange site has a "meta" section where users can settle disputes, in the style of
MetaFilter
MetaFilter, known as MeFi to its members, is a general-interest community weblog, founded in 1999 and based in the United States, featuring links to content that users have discovered on the web. Since 2003, it has included the popular question-a ...
's "MetaTalk" forum, because the self-moderation system for questions and answers can lead to significant arguments.
Badges are awarded for asking and answering, participating in meta, and for moderating the site. There are bronze, silver and gold badges and appear on users' profile pages as well as their posts.
Moderators and election process
Moderators are responsible for managing the site, such as by following up on flagged posts, locking and protecting posts, suspending users, and deleting the worst posts on the site. According to the Stack Exchange philosophy, they should be minimally involved in the site. They are also expected to lead by example, as well as to show respect to other users.
To become a moderator, users have to participate in an election. Elections are called as needed by the Stack Exchange Community Team for a designated number of seats. Users must first nominate themselves and have at least 300 reputation (3,000 on Stack Overflow and 1,000 on Math Stack Exchange), while also being in good standing, such as not having been suspended during the past year. Aside from introducing themselves and explaining why they would be a good moderator, users must also answer questions written by the community. Nominations can be withdrawn at any time.
After this, users vote on the candidates in a primary, where the vote tally is made public. The top 10 nominees advance to the election stage, where any user with at least 150 reputation is allowed to vote. A ranked-choice voting system is used where users can rank all the candidates if they wish. Votes are tallied using the Meek STV method (single transferable vote) which allows fractional parts of a vote to be counted.
Bounties
Stack Exchange allows users to donate some of their reputation to help questions receive answers or better answers, as well as to incentivize users to answer. This is called a 'bounty' and can be applied on questions 48 hours after being asked, lasting for 7 days plus a grace period of 24 hours. The minimum bounty is set at 50 reputation, except if the user has already answered the question or has offered a previous bounty on the question. Bounties cannot be cancelled, and reputation cannot be refunded from a bounty, even if the question did not receive an answer.
Criticism
Trustpilot
Trustpilot Group plc, is a Danish consumer business operating a review website founded in Denmark in 2007 which hosts reviews of businesses worldwide. Nearly 1 million new reviews are posted each month. The site offers freemium services to busine ...
's page on
Stack Overflow
In software, a stack overflow occurs if the call stack pointer exceeds the stack bound. The call stack may consist of a limited amount of address space, often determined at the start of the program. The size of the call stack depends on many facto ...
, the largest Stack Exchange, shows an average rating of 2.2 stars out of 5, a "Poor" rating. Although 30% of reviewers gave the site a good score, 67% of 136 reviewers gave the site a bad review of 2 stars or fewer. The website was accused by many users of having aggressive moderation that tended to exclude newcomers with lesser programming knowledge.
Technologies used
Stack Exchange uses
IIS,
SQL Server,
and the
ASP.NET
ASP.NET is an open-source, server-side web-application framework designed for web development to produce dynamic web pages. It was developed by Microsoft to allow programmers to build dynamic web sites, applications and services. The name s ...
framework,
all from a single code base for every Stack Exchange site (except Area 51, which runs off a fork of the Stack Overflow code base). Blogs formerly used
WordPress
WordPress (WP or WordPress.org) is a free and open-source content management system (CMS) written in hypertext preprocessor language and paired with a MySQL or MariaDB database with supported HTTPS. Features include a plugin architecture ...
, but they have been discontinued. The team also uses
Redis,
HAProxy and
Elasticsearch
Elasticsearch is a search engine based on the Lucene library. It provides a distributed, multitenant-capable full-text search engine with an HTTP web interface and schema-free JSON documents. Elasticsearch is developed in Java and is dual ...
.
Stack Exchange tries to stay up to date with the newest technologies from
Microsoft
Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washin ...
, usually using the latest releases of any given framework. The code is primarily written in C# ASP.NET MVC using the
Razor View Engine. The preferred
IDE is
Visual Studio
Visual Studio is an integrated development environment (IDE) from Microsoft. It is used to develop computer programs including websites, web apps, web services and mobile apps. Visual Studio uses Microsoft software development platforms such ...
and the data layers uses
Dapper for data access.
The site makes use of
URL slug
Clean URLs, also sometimes referred to as RESTful URLs, user-friendly URLs, pretty URLs or search engine-friendly URLs, are URLs intended to improve the usability and accessibility of a website or web service by being immediately and intuitivel ...
s in addition to numeric
identifiers for question URLs.
Site creation process
Every new site created in the Stack Exchange Network goes through a detailed review process consisting of six steps:
# Discussion: The Stack Exchange meta site should provide a forum for discussing potential new ideas labeled a future Stack Exchange site.
# Proposal: A public proposal must be drafted and posted so that any member of the community can discuss the proposal and vote on it. This allows a collaborative proposal to emerge over time. The proposal must address these four key issues:
## the topic of the site
## the targeted audience
## forty exemplary questions, upvoted at least 10 times from the community
## 60 followers from the community
# Commitment: 200 users interested in the new site are asked to formally commit and support the site by actively participating and contributing to it by asking or answering 10 questions during th
FIRDRsix months of the public beta.
# Private Beta: If the concept receives 100% commitment, the site enters the private beta phase, where committed members begin actively using the site and publicizing it.
# Public Beta: The site is open to the public for a long period. This allows the creators to ensure that the site reaches critical mass before it is fully launched.
# Graduation: The site is evaluated on multiple criteria such as the number of answered questions, new questions per day, and registered users. If it meets these criteria and is deemed "sustainable", it is granted a "graduation" and fully launched.
Notable users
Nobel Prize winners
*
Gerard 't Hooft
Gerardus (Gerard) 't Hooft (; born July 5, 1946) is a Dutch theoretical physicist and professor at Utrecht University, the Netherlands. He shared the 1999 Nobel Prize in Physics with his thesis advisor Martinus J. G. Veltman "for elucidating th ...
Fields Medal winners
*
Peter Scholze
Peter Scholze (; born 11 December 1987) is a German mathematician known for his work in arithmetic geometry. He has been a professor at the University of Bonn since 2012 and director at the Max Planck Institute for Mathematics since 2018. He ha ...
(2018)
*
Martin Hairer
Sir Martin Hairer (born 14 November 1975) is an Austrian-British mathematician working in the field of stochastic analysis, in particular stochastic partial differential equations. He is Professor of Mathematics at EPFL (École Polytechnique F ...
(2014)
*
Terence Tao (2006)
*
Tim Gowers (1998)
*
Curtis McMullen (1998)
*
Richard Borcherds
Richard Ewen Borcherds (; born 29 November 1959) is a British mathematician currently working in quantum field theory. He is known for his work in lattices, group theory, and infinite-dimensional algebras, for which he was awarded the Fields M ...
(1998)
*
Edward Witten
Edward Witten (born August 26, 1951) is an American mathematical and theoretical physicist. He is a Professor Emeritus in the School of Natural Sciences at the Institute for Advanced Study in Princeton. Witten is a researcher in string theory, q ...
(1990)
*
Vaughan Jones (1990)
*
Michael Freedman
Michael Hartley Freedman (born April 21, 1951) is an American mathematician, at Microsoft Station Q, a research group at the University of California, Santa Barbara. In 1986, he was awarded a Fields Medal for his work on the 4-dimensional gene ...
(1986)
*
William Thurston
William Paul Thurston (October 30, 1946August 21, 2012) was an American mathematician. He was a pioneer in the field of low-dimensional topology and was awarded the Fields Medal in 1982 for his contributions to the study of 3-manifolds.
Thursto ...
(1982)
Founders
*
Joel Spolsky
Avram Joel Spolsky (born 1965) is a software engineer and writer. He is the author of ''Joel on Software'', a blog on software development, and the creator of the project management software Trello. He was a Program Manager on the Microsoft Exce ...
(co-founder of
Stack Overflow
In software, a stack overflow occurs if the call stack pointer exceeds the stack bound. The call stack may consist of a limited amount of address space, often determined at the start of the program. The size of the call stack depends on many facto ...
)
*
Jeff Atwood
Jeff Atwood (1970) is an American software developer, author, blogger, and entrepreneur. He co-founded the computer programming question-and-answer website Stack Overflow and co-founded Stack Exchange, which extends Stack Overflow's question-a ...
(co-founder of Stack Overflow)
*
Ravi Vakil
Ravi D. Vakil (born February 22, 1970) is a Canadian-American mathematician working in algebraic geometry.
Education and career
Vakil attended high school at Martingrove Collegiate Institute in Etobicoke, Ontario, where he won several mathemati ...
(co-founder of
MathOverflow
MathOverflow is a mathematics question-and-answer (Q&A) website, which serves as an online community of mathematicians. It allows users to ask questions, submit answers, and rate both, all while getting merit points for their activities. It is a ...
)
Other notable scientists and mathematicians
*
Scott Aaronson
Scott Joel Aaronson (born May 21, 1981) is an American theoretical computer scientist and David J. Bruton Jr. Centennial Professor of Computer Science at the University of Texas at Austin. His primary areas of research are quantum computing a ...
*
Ian Agol
Ian Agol (born May 13, 1970) is an American mathematician who deals primarily with the topology of three-dimensional manifolds.
Education and career
Agol graduated with B.S. in mathematics from the California Institute of Technology in 1992 and ...
*
John Baez
John Carlos Baez (; born June 12, 1961) is an American mathematical physicist and a professor of mathematics at the University of California, Riverside (UCR) in Riverside, California. He has worked on spin foams in loop quantum gravity, appl ...
*
Carlo Beenakker
*
Andreas Blass
Andreas Raphael Blass (born October 27, 1947) is a mathematician, currently a professor at the University of Michigan. He works in mathematical logic, particularly set theory, and theoretical computer science.
Blass graduated from the University ...
*
Robert Bryant
*
Noam Elkies
Noam David Elkies (born August 25, 1966) is a professor of mathematics at Harvard University. At the age of 26, he became the youngest professor to receive tenure at Harvard. He is also a pianist, chess national master and a chess composer.
Ear ...
*
Matthew Emerton
*
Alexandre Eremenko
Alexandre Eremenko (born 1954 in Kharkiv, Ukraine; ua, Олександр Емануїлович Єременко, transcription: Olexandr Emanuilowitsch Jeremenko) is a Ukrainian- American mathematician who works in the fields of complex analy ...
*
Joel David Hamkins (top user on
MathOverflow
MathOverflow is a mathematics question-and-answer (Q&A) website, which serves as an online community of mathematicians. It allows users to ask questions, submit answers, and rate both, all while getting merit points for their activities. It is a ...
)
*
James E. Humphreys
*
Gil Kalai
Gil Kalai (born 1955) is the Henry and Manya Noskwith Professor Emeritus of Mathematics at the Hebrew University of Jerusalem, Israel, Professor of Computer Science at the Interdisciplinary Center, Herzliya, and adjunct Professor of mathematics ...
*
Anna Krylov
*
Greg Kuperberg
Greg Kuperberg (born July 4, 1967) is a Polish-born American mathematician known for his contributions to geometric topology, quantum algebra, and combinatorics. Kuperberg is a professor of mathematics at the University of California, Davis.Greg ...
*
Joseph O'Rourke
*
Igor Rivin
*
Jeffrey Shallit
Jeffrey Outlaw Shallit (born October 17, 1957) is a computer scientist, number theorist, and a noted critic of intelligent design. He is married to Anna Lubiw, also a computer scientist.
Early life and education
Shallit was born in Philadelp ...
(computer scientist with
Erdos number of one)
*
Peter Shor
Peter Williston Shor (born August 14, 1959) is an American professor of applied mathematics at MIT. He is known for his work on quantum computation, in particular for devising Shor's algorithm, a quantum algorithm for factoring exponentially f ...
(inventor of
Shor's algorithm
Shor's algorithm is a quantum computer algorithm for finding the prime factors of an integer. It was developed in 1994 by the American mathematician Peter Shor.
On a quantum computer, to factor an integer N , Shor's algorithm runs in polynom ...
)
*
Michael Shulman
*
Anders Sandberg
Anders Sandberg (born 11 July 1972) is a Swedish researcher, futurist and transhumanist. He holds a PhD in computational neuroscience from Stockholm University, and is currently a senior research fellow at the Future of Humanity Institute at th ...
See also
*
MathOverflow
MathOverflow is a mathematics question-and-answer (Q&A) website, which serves as an online community of mathematicians. It allows users to ask questions, submit answers, and rate both, all while getting merit points for their activities. It is a ...
*
PhysicsOverflow
PhysicsOverflow is a physics website that serves as a post-publication open peer review platform for research papers in physics, as well as a collaborative blog and online community of physicists. It allows users to ask, answer and comment on gr ...
*
Q&A software
Q&A software is online software that attempts to answer questions asked by users (Q&A stands for "question and answer"). Q&A software is frequently integrated by large and specialist corporations and tends to be implemented as a community that all ...
References
External links
*
List of Stack Exchange sites
{{Fog Creek Software
Companies based in New York City
Computing websites
Creative Commons-licensed websites
Internet properties established in 2008
Question-and-answer websites
Software developer communities
Stack Exchange network