Reddit is a major American discussion platform where users write posts, comment, and rate content through a voting system. Since its 2024 IPO, Reddit is regarded above all as a valuable source of text used to train AI systems.
Reddit is a website where people write posts and discuss them. The site is divided into thousands of topic areas called subreddits. They exist for almost everything: cooking, stocks, football, math homework, or repair tips for washing machines. Every user can rate a post or a comment with an upvote or a downvote. What many people upvote rises to the top and gets read by many. Reddit is among the ten most-visited websites in the world and has more than 100 million active daily users.
Why a forum suddenly became interesting to AI companies
Large AI systems learn from huge amounts of text. For this they don’t need just any sentences, but the most authentic, human language possible. Reddit delivers exactly that: millions of questions and the corresponding answers, written by real people in ordinary everyday tone. On top of that comes the rating system, which provides a kind of quality judgment. An answer with 5,000 upvotes was evidently helpful to other people.
This very advantage comes with a price. For years, companies were allowed to scrape the posts for free. In 2023 Reddit changed the rules and suddenly demanded a lot of money for automated access to its data. Many popular third-party add-on apps had to shut down as a result. Thousands of volunteers who manage individual subreddits set their areas to private temporarily in protest.
Afterward came deals with major technology companies. Google and OpenAI pay for access to the content, reportedly in the range of several tens of millions of dollars per year. For investors, Reddit thus became an example of a new business model: not just selling advertising, but also selling training data. At the IPO in March 2024, this was one of the most important selling points.
Subreddits, karma, and moderation
A subreddit is a distinct area with its own name, written as r/ followed by the topic, for example r/germany. Anyone can create such an area. Whoever creates it also sets the rules and ensures they are followed. These moderators are almost always volunteers and are not paid by Reddit.
Users' ratings add up to a score called karma. Karma is not money and cannot be paid out. It only shows how often someone’s posts resonated with others. Posts with many votes rise to the front page, poorly rated ones slide down and disappear. This sorting by the users themselves is the core of the platform.
A common misconception: many upvotes do not mean something is true. They only mean that many people liked the post. False but entertaining answers rise to the top just as much as correct ones. Anyone using Reddit texts as training material therefore also inherits errors, sarcasm, and biases.
Reddit in Google search and in AI answers
You have probably encountered Reddit already without deliberately visiting the site. Many people add the word reddit to their Google search because they’re looking for genuine first-hand accounts instead of advertising copy. Google responded to this and often shows Reddit posts high up in search results. That made the platform even more valuable.
Even when you ask a chatbot for a travel tip or a purchase recommendation, part of the knowledge behind it comes from forums like these. A well-known mishap demonstrated this: in 2024, Google’s AI summary recommended using glue to help cheese stick to pizza. The source was an old Reddit comment obviously meant as a joke.
Reddit also appears in business news as a stock market topic. The subreddit r/wallstreetbets became famous in 2021, when thousands of small investors coordinated there and drove up the price of GameStop stock. Since then, analysts have watched such forums closely. Reddit is thus simultaneously a data supplier, a publicly traded company, and a place where market movements originate.