computer science

Stack Overflow

Stack Overflow is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Stack Overflow rather than just read about it. In short: Stack Overflow is a question-and-answer website for computer programmers. Created in 2008 by Jeff Atwood and Joel Spolsky, it is the flagship site of the Stack Exchange network.

Key takeaways

Stack Overflow belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Stack Overflow to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Stack Overflow from memory before moving on to harder problems.

Reference excerpt

Stack Overflow is a question-and-answer website for computer programmers. Created in 2008 by Jeff Atwood and Joel Spolsky, it is the flagship site of the Stack Exchange network. Stack Overflow features questions and answers on certain computer programming topics, and was created to be a more open alternative to earlier question-and-answer websites such as Experts-Exchange. The website was sold to Prosus, a Netherlands-based consumer-internet conglomerate, on 2 June 2021 for US$1.8 billion. Stack Overflow 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 similar to Reddit and edit questions and answers in a fashion similar to a wiki. Users of the website can earn reputation points and "badges"; for example, a person is awarded 10 reputation points for receiving an "up" vote on a question or an answer to a question, and can receive badges for their valued contributions, which represents a gamification of the traditional Q&A website. Users unlock new privileges with an increase in reputation like the ability to vote, comment, and even edit other people's posts. As of June 2025, Stack Overflow has over 29 million registered users, and has received over 24 million questions and 36 million answers. The site and similar programming question-and-answer sites globally largely replaced programming books for day-to-day programming reference in the 2000s, and were an important part of computer programming. 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.

History

The website was created by Jeff Atwood and Joel Spolsky in 2008. The name for the website was chosen by voting in April 2008 by readers of Coding Horror, Atwood's programming blog. 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. 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. In 2019, Stack Overflow named Prashanth Chandrasekar as its chief executive officer and Teresa Dietrich as its chief product officer. In June 2021, Prosus, a Netherlands-based subsidiary of South African media company Naspers, announced a deal to acquire Stack Overflow for $1.8 billion.

Security breach 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 184 public network users were affected by this breach, which "could have returned IP address, names, or emails".

2023 controversy over AI-generated content and moderation strike

Content 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 softwareengineering.stackexchange.com is intended to be a venue for broader queries, e.g. general questions about software development. Closing questions is a main differentiation from other Q&A sites like Yahoo! Answers and a way to prevent low quality questions. The mechanism was overhauled in 2013; questions edited after being put "on hold" now appear in a review queue. 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. All user-generated content is licensed under Creative Commons Attribute-ShareAlike license, version 2.5, 3.0, or 4.0 depending on the date the content was contributed.

Statistics

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. 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. As of 2011, 92% of the questions were answered, in a median time of 11 minutes. As of August 2012, 443,000 of the 1.3 million 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. 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. As of January 2026, new questions posted to the platform had declined significantly from the site's peak of 200,000 questions per month in 2014. Questions submitted by users fell 78% between December 2024 and December 2025. According to some, the site's perceived hostile moderation culture, as well as competition from generative AI tools, have contributed to this decline.

Technology Stack Overflow is written in C# using the ASP.NET MVC (Model–View–Controller) framework, and Microsoft SQL Server for the database and the Dapper object–relational mapper used for data access. 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.

… excerpt ends here. Continue reading the full article.

Illustrations

Logo until February 2026[18]

Worked examples

Example 1 — a first encounter with Stack Overflow

Start with the simplest possible case. Write down what Stack Overflow claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Stack Overflow before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Stack Overflow ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Stack Overflow

In research: Stack Overflow appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Stack Overflow in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Stack Overflow is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2021 mergers and acquisitions, Computing websites, Gamification, so understanding it makes those chapters shorter.
In everyday life: Look for Stack Overflow outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Stack Overflow in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Stack Overflow means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Stack Overflow out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Stack Overflow in simple terms?

Stack Overflow is a question-and-answer website for computer programmers. Created in 2008 by Jeff Atwood and Joel Spolsky, it is the flagship site of the Stack Exchange network.

Why does Stack Overflow matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Stack Overflow?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Stack Overflow.