ChatGPT
ChatGPT is a generative artificial intelligence chatbot developed by OpenAI. It was released in November 2022. It uses generative pre-trained transformers, such as GPT-5, to generate text, speech, and images in response to user prompts. It is credited with accelerating the AI boom, an ongoing period marked by rapid investment and public attention toward the field of artificial intelligence. OpenAI operates the service on a freemium model. Users can interact with ChatGPT through text, audio, and image prompts.
The service gained 100 million users in two months, making it the fastest-growing consumer software application in history. ChatGPT's website is among the top 5 most-visited websites globally. It has been lauded for its potential to transform numerous professional fields, and instigated public debate about the nature of creativity and the future of knowledge work.
The chatbot has also been criticized for its limitations and potential for unethical use. It can generate plausible-sounding but incorrect or nonsensical answers, known as hallucinations. Biases in its training data have been reflected in its responses. The chatbot can facilitate academic dishonesty, generate misinformation, and create malicious code. The ethics of its development, particularly the use of copyrighted content as training data, have also drawn controversy.
Training
ChatGPT is based on GPT foundation models that have been fine-tuned for conversational assistance. The fine-tuning process involved supervised learning and reinforcement learning from human feedback. Both approaches employed human trainers to improve model performance. In the case of supervised learning, the trainers acted as both the user and the AI assistant. In the reinforcement learning stage, human trainers first ranked responses generated by the model in previous conversations. These rankings were used to create "reward models" that were used to fine-tune the model further by using several iterations of proximal policy optimization.To build a safety system against harmful content, OpenAI used outsourced Kenyan workers, earning around $1.32 to $2per hour, to label such content. These labels were used to train a model to detect such content in the future. The laborers were exposed to toxic and traumatic content; one worker described the assignment as "torture". OpenAI's outsourcing partner was Sama, a training-data company based in San Francisco, California.OpenAI collects data from ChatGPT users to further train and fine-tune its services. Users can upvote or downvote responses they receive from ChatGPT, and can fill in a text field with additional feedback.
ChatGPT's training data includes software manual pages, information about internet phenomena such as bulletin board systems, multiple programming languages, and the text of Wikipedia.
Features
ChatGPT is a chatbot and AI assistant built on large language model technology. It is designed to generate human-like text and can carry out a wide variety of tasks. These include, among many others, writing and debugging computer programs, composing music, scripts, fairy tales, and essays, answering questions, and generating business concepts.ChatGPT is frequently used for translation and summarization tasks, and can simulate interactive environments such as a Linux terminal, a multi-user chat room, or simple text-based games such as tic-tac-toe.
Users interact with ChatGPT through conversations which consist of text, audio, and image inputs and outputs. The user's inputs to these conversations are referred to as prompts. An optional "Memory" feature allows users to tell ChatGPT to memorize specific information. Another option allows ChatGPT to recall old conversations. GPT-based moderation classifiers are used to reduce the risk of harmful outputs being presented to users.
In March 2023, OpenAI added support for plugins for ChatGPT. This includes both plugins made by OpenAI, such as web browsing and code interpretation, and external plugins from developers such as Expedia, OpenTable, Zapier, Shopify, Slack, and Wolfram.
In October 2024, ChatGPT Search was introduced. It allows ChatGPT to search the web in an attempt to make more accurate and up-to-date responses.
In December 2024, OpenAI launched a new feature allowing users to call ChatGPT with a telephone for up to 15 minutes per month for free.
In September 2025, OpenAI added a feature called Pulse, which generates a daily analysis of a user's chats and connected apps such as Gmail and Google Calendar.
In October 2025, OpenAI launched ChatGPT Atlas, a browser integrating the ChatGPT assistant directly into web navigation, to compete with existing browsers such as Google Chrome and Safari. It has an additional feature called "agentic mode" that allows it to take online actions for the user.
Paid tier
ChatGPT was initially free to the public and remains free in a limited capacity. In February 2023, OpenAI launched a premium service, ChatGPT Plus, that costs per month. According to the company, Plus provided access during peak periods, no downtime, priority access to new features, and faster response speeds. OpenAI later introduced the subscription plans "ChatGPT Team" and "ChatGPT Enterprise". What was offered on the paid plan versus the free tier changed as OpenAI has continued to update ChatGPT, and a Pro tier at $200/mo was introduced in December 2024. The Pro launch coincided with the release of the o1 model. In August 2025, ChatGPT Go was offered in India for ₹399 per month. The plan has higher limits than the free version.Mobile apps
In May-July 2023, OpenAI began offering ChatGPT iOS and Android apps. ChatGPT can also power Android's assistant.An app for Windows launched on the Microsoft Store on October 15, 2024.
Infrastructure
ChatGPT initially used a Microsoft Azure infrastructure which was powered by a supercomputer that Microsoft built specifically for OpenAI, equipped with thousands of GPUs manufactured by Nvidia, costing hundreds of millions of dollars. Following ChatGPT's success, Microsoft upgraded the OpenAI infrastructure in 2023. TrendForce estimated that 30,000 Nvidia GPUs were used to power ChatGPT in 2023.Scientists at the University of California, Riverside, estimated in 2023 that a series of 5 to 50 prompts to ChatGPT needs approximately of water for Microsoft servers' cooling.
Languages
OpenAI met Icelandic President Guðni Th. Jóhannesson in 2022. In 2023, OpenAI worked with a team of 40 Icelandic volunteers to fine-tune ChatGPT's Icelandic conversation skills as a part of Iceland's attempts to preserve the Icelandic language.ChatGPT was better able to translate Japanese to English when compared to Bing, Bard, and DeepL Translator in 2023. Researchers suggested this was due to its higher ability to capture the context.
In December 2023, the Albanian government decided to use ChatGPT for the rapid translation of European Union documents and the analysis of required changes needed for Albania's accession to the EU.
Several studies have shown that ChatGPT can outperform Google Translate in some mainstream translation tasks. However, no machine translation services match human expert performance.
In August 2024, a representative of the Asia Pacific wing of OpenAI made a visit to Taiwan, during which a demonstration of ChatGPT's Chinese abilities was made. ChatGPT's Mandarin Chinese abilities were lauded, but the ability of the AI to produce content in Mandarin Chinese in a Taiwanese accent was found to be "less than ideal" due to differences between mainland Mandarin Chinese and Taiwanese Mandarin.
GPT Store
In November 2023, OpenAI released GPT Builder a tool for users to customize ChatGPT's behavior for a specific use case. The customized systems are referred to as GPTs. In January 2024, OpenAI launched the GPT Store, a marketplace for GPTs. At launch, OpenAI included more than 3 million GPTs created by GPT Builder users in the GPT Store.Deep Research
In February 2025, OpenAI released Deep Research. According to TechCrunch, it is a service based on o3 that combines advanced reasoning and web search capabilities to make comprehensive reports within 5 to 30 minutes.Images
In October 2023, OpenAI's image generation model DALL-E 3 was integrated into ChatGPT. The integration used ChatGPT to write prompts for DALL-E guided by conversations with users.In March 2025, OpenAI updated ChatGPT to generate images using GPT Image instead of DALL-E. One of the most significant improvements was in the generation of text within images, which is especially useful for branded content. However, this ability is noticeably worse in non-Latin alphabets. The model can also generate new images based on existing ones provided in the prompt. These images are generated with C2PA metadata, which can be used to verify that they are AI-generated. OpenAI has emplaced additional safeguards to prevent what the company deems to be harmful image generation.
Agents
In 2025, OpenAI added several features to make ChatGPT more agentic. In January, Operator was released. It was capable of autonomously performing tasks through web browser interactions, including filling forms, placing online orders, scheduling appointments, and other browser-based tasks. It was controlling a software environment inside a virtual machine with limited internet connectivity and with safety restrictions. It struggled with complex user interfaces.In May 2025, OpenAI introduced an agent for coding named Codex. It is capable of writing software, answering codebase questions, running tests, and proposing pull requests. It is based on a fine-tuned version of OpenAI o3. It has two versions, one running in a virtual machine in the cloud, and one where the agent runs in the cloud, but performs actions on a local machine connected via API.
In July 2025, OpenAI released ChatGPT agent, an AI agent that can perform multi-step tasks. Like Operator, it controls a virtual computer. It also inherits from Deep Research's ability to gather and summarize significant volumes of information. The user can interrupt tasks or provide additional instructions as needed.
In September 2025, OpenAI partnered with Stripe, Inc. to release Agentic Commerce Protocol, enabling purchases through ChatGPT. At launch, the feature was limited to purchases on Etsy from US users with a payment method linked to their OpenAI account. OpenAI takes an undisclosed cut from the merchant's payment.