> For the complete documentation index, see [llms.txt](https://book.konstantinsecurity.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.konstantinsecurity.com/readme/machine-learning/chat-bots/chat-gpt.md).

# Chat GPT

<https://chat.openai.com/chat>

**ChatGPT**, which stands for **Chat Generative Pre-trained Transformer**, is a [large language model](https://en.wikipedia.org/wiki/Large_language_model)-based [chatbot](https://en.wikipedia.org/wiki/Chatbot) developed by [OpenAI](https://en.wikipedia.org/wiki/OpenAI) and launched on November 30, 2022, which enables users to refine and steer a conversation towards a desired length, format, style, level of detail, and language. Successive prompts and replies, known as [prompt engineering](https://en.wikipedia.org/wiki/Prompt_engineering), are considered at each conversation stage as a context.[\[2\]](https://en.wikipedia.org/wiki/ChatGPT#cite_note-guardianpos-2)

ChatGPT is built upon either [GPT-3.5](https://en.wikipedia.org/wiki/GPT-3.5) or [GPT-4](https://en.wikipedia.org/wiki/GPT-4)—members of OpenAI's proprietary series of [generative pre-trained transformer](https://en.wikipedia.org/wiki/Generative_pre-trained_transformer) (GPT) models, based on the [transformer](https://en.wikipedia.org/wiki/Transformer_\(machine_learning_model\)) architecture developed by [Google](https://en.wikipedia.org/wiki/Google)[\[3\]](https://en.wikipedia.org/wiki/ChatGPT#cite_note-3)—and is [fine-tuned](https://en.wikipedia.org/wiki/Fine-tuning_\(machine_learning\)) for conversational applications using a combination of [supervised](https://en.wikipedia.org/wiki/Supervised_learning) and [reinforcement learning](https://en.wikipedia.org/wiki/Reinforcement_learning) techniques.[\[4\]](https://en.wikipedia.org/wiki/ChatGPT#cite_note-NYT-20230718-4) ChatGPT was released as a freely available research preview, but due to its popularity, OpenAI now operates the service on a [freemium model](https://en.wikipedia.org/wiki/Freemium). It allows users on its free tier to access the GPT-3.5-based version. In contrast, the more advanced GPT-4 based version and priority access to newer features are provided to paid subscribers under the commercial name "[ChatGPT Plus](https://en.wikipedia.org/wiki/ChatGPT_Plus)".

By January 2023, it had become what was then the fastest-growing consumer software application in history, gaining over 100 million users and contributing to OpenAI's [valuation](https://en.wikipedia.org/wiki/Business_valuation) growing to $29 billion.[\[5\]](https://en.wikipedia.org/wiki/ChatGPT#cite_note-5)[\[6\]](https://en.wikipedia.org/wiki/ChatGPT#cite_note-6) Within months, Google, [Baidu](https://en.wikipedia.org/wiki/Baidu), and [Meta](https://en.wikipedia.org/wiki/Meta_Platforms) accelerated the development of their competing products: [Bard](https://en.wikipedia.org/wiki/Bard_\(chatbot\)), [Ernie Bot](https://en.wikipedia.org/wiki/Ernie_Bot), and [LLaMA](https://en.wikipedia.org/wiki/LLaMA).[\[7\]](https://en.wikipedia.org/wiki/ChatGPT#cite_note-7) Microsoft launched its [Bing Chat](https://en.wikipedia.org/wiki/Bing_Chat) based on OpenAI's GPT-4. It raised concern among some observers over the potential of ChatGPT and similar programs to displace or atrophy [human intelligence](https://en.wikipedia.org/wiki/Human_intelligence), enable [plagiarism](https://en.wikipedia.org/wiki/Plagiarism), or fuel [misinformation](https://en.wikipedia.org/wiki/Misinformation).[\[4\]](https://en.wikipedia.org/wiki/ChatGPT#cite_note-NYT-20230718-4)[\[8\]](https://en.wikipedia.org/wiki/ChatGPT#cite_note-8)

[Implementing GPT in NumPy](/readme/machine-learning/chat-bots/chat-gpt/implementing-gpt-in-numpy.md)