GPT-5
In plain wordsOpenAI's flagship AI model from August 2025, which decides by itself whether to answer quickly or think longer. It replaced earlier models in ChatGPT and was followed by frequent upgrades.
A large language modellarge language model, n.: A computer program trained on enormous amounts of text to predict the words that come next. At vast scale, that simple skill lets it chat, answer questions, translate, summarize and write code. system released by OpenAIOpenAI, prop. n.: The American company that makes ChatGPT and the GPT models. It began in 2015 as a nonprofit research lab and is now a for-profit company overseen by a nonprofit foundation. on 7 August 2025 that merged its GPT line with its o-series reasoning modelsreasoning model, n.: An AI model trained to work through a problem step by step in hidden 'thinking' text before it answers. Letting it think longer generally makes it better at math, coding and planning.. Inside ChatGPT, an automatic router decides for each message whether a quick model will do or whether to pass it to a slower 'thinking' model, weighing whether the user has asked for careful reasoning, how hard the request looks and what sort of conversation it is; API customers instead pick a size (GPT-5, mini or nano) and set the reasoning effort themselves. OpenAI reported large gains in coding, mathematics and health questions and reductions in hallucinationhallucination, n.: When an AI states something false or made up — a fake fact, quotation or source — fluently and confidently, as if it were true. and sycophancysycophancy, n.: When an AI tells people what they want to hear — flattering them, agreeing with their mistakes or dropping a correct answer under pushback — instead of what is true or useful., and made GPT-5 the default for all ChatGPT users. The simultaneous removal of GPT-4oGPT-4o, prop. n.: An OpenAI model from 2024 that handles text, images and speech in one system, enabling fast, natural voice conversations. Many users grew attached to its personality, which made its retirement controversial. provoked a user backlash, and OpenAI restored it for paying subscribers within days. Point releases followed at a fast pace — GPT-5.1 in November 2025, GPT-5.2 in December 2025 and later versions including GPT-5.5 by mid-2026 — before OpenAI released GPT-6 in early September 2026.
The router answered my quick question instantly, but GPT-5 thought for a minute about the proof.
Origin
Long anticipated after GPT-4GPT-4, prop. n.: OpenAI's 2023 language model, a big step up from the one behind the first ChatGPT. It scored well on many professional and academic exams and could also read images. (2023); Sam Altman had described it as the release that would unify the GPT and o-series lines. Announced in a livestream on 7 August 2025, two days after OpenAI released its first open-weight models since GPT-2, the gpt-oss family.
Usage note
Reactions were mixed: benchmark gains were real, but many users had expected a larger leap, and the launch fed debate over whether progress was slowing; others pointed to its gains in agentic coding and in efficient use of reasoning.
Related
- OpenAI o1OpenAI o1, prop. n.: OpenAI's first reasoning model, from 2024. Before replying it writes out a long, hidden series of steps, trying ideas and checking them, which lifted its scores on hard math, science and coding problems far above earlier chatbots'.
- OpenAI o3OpenAI o3, prop. n.: OpenAI's second-generation reasoning model, announced in December 2024. Its high scores on a puzzle test designed to resist AI made headlines, and the released version could use tools such as web search while thinking.
- GPT-4GPT-4, prop. n.: OpenAI's 2023 language model, a big step up from the one behind the first ChatGPT. It scored well on many professional and academic exams and could also read images.
- ChatGPTChatGPT, prop. n.: OpenAI's AI chatbot, released free to the public in November 2022, which answers questions, writes and converses in everyday language. Its sudden popularity began the current AI boom.
- reasoning modelreasoning model, n.: An AI model trained to work through a problem step by step in hidden 'thinking' text before it answers. Letting it think longer generally makes it better at math, coding and planning.
- frontier modelfrontier model, n.: One of the most capable AI models in existence at a given time, built by a handful of leading labs at great cost, and the main target of AI safety rules.
- OpenAIOpenAI, prop. n.: The American company that makes ChatGPT and the GPT models. It began in 2015 as a nonprofit research lab and is now a for-profit company overseen by a nonprofit foundation.
Sources
- OpenAI (2025). Introducing GPT-5. OpenAI blog, 7 August 2025.
- OpenAI (2025). GPT-5 System Card. August 2025.
Mentioned in
ChatGPTChatGPT, prop. n.: OpenAI's AI chatbot, released free to the public in November 2022, which answers questions, writes and converses in everyday language. Its sudden popularity began the current AI boom., OpenAIOpenAI, prop. n.: The American company that makes ChatGPT and the GPT models. It began in 2015 as a nonprofit research lab and is now a for-profit company overseen by a nonprofit foundation., GPT-4oGPT-4o, prop. n.: An OpenAI model from 2024 that handles text, images and speech in one system, enabling fast, natural voice conversations. Many users grew attached to its personality, which made its retirement controversial., OpenAI o1OpenAI o1, prop. n.: OpenAI's first reasoning model, from 2024. Before replying it writes out a long, hidden series of steps, trying ideas and checking them, which lifted its scores on hard math, science and coding problems far above earlier chatbots'., model deprecationmodel deprecation, n.: When an AI company announces that an older model will stop being offered and then switches it off, so the apps and people relying on it must move to a newer one., OpenAI o3OpenAI o3, prop. n.: OpenAI's second-generation reasoning model, announced in December 2024. Its high scores on a puzzle test designed to resist AI made headlines, and the released version could use tools such as web search while thinking.