GPT: GPT stands for generative pre-trained transformer, the family of large language models from OpenAI that powers ChatGPT. The name describes how the models are built: they generate text, are pre-trained on huge datasets, and use the transformer architecture.
Each word in the name matters. Generative: the model produces new text rather than classifying existing text. Pre-trained: it learned from a massive general corpus before being tuned for specific behavior. Transformer: it uses the attention-based neural network architecture introduced in 2017. Many competing models share all three traits, but GPT is OpenAI's brand for its series.
OpenAI released the first GPT in 2018 and has shipped successively larger and more capable versions since. ChatGPT, launched in November 2022, wrapped a GPT model in a chat interface and is what made the term famous. OpenAI also lets users build custom GPTs, which are configured versions of ChatGPT with their own instructions and files.
People often say 'GPT' to mean any AI chatbot, but Anthropic's Claude, Google's Gemini, and Meta's Llama models are separate model families built by different companies. Microsoft's Copilot products have relied heavily on OpenAI models through the companies' partnership. Knowing which model sits under a product helps when you compare tools or read a vendor's data policy.
Example at work
A small-business owner uses ChatGPT for daily drafting, then builds a custom GPT loaded with her price list and service descriptions so her office manager can generate consistent quotes. Both run on OpenAI's GPT models; the custom version simply carries standing instructions and reference files.
Why it matters
GPT is the most recognized name in AI, and understanding what it stands for gives you a compact summary of how modern language models work. It also helps you avoid treating a brand name as a category, so you evaluate tools on their actual model, features, and terms.
Related terms
- Large language model (LLM)A large language model (LLM) is a neural network trained on enormous amounts of text to predict the next word, then tuned to follow instructions and hold a conversation. LLMs power ChatGPT, Claude, Gemini, and Microsoft Copilot.
- TransformerThe transformer is the neural network architecture behind nearly all modern language models. Its key idea, called attention, lets the model weigh every word in a passage against every other word, so it can track meaning across long stretches of text.
- Pre-trainingPre-training is the first and largest phase of building an AI model, in which it learns general patterns from a massive dataset, such as predicting the next word across trillions of words of text. Later phases then shape it into a useful assistant.
- Custom GPTA custom GPT is a tailored version of ChatGPT that you configure with your own instructions, uploaded reference files, and optional connections to outside services, then reuse or share without rewriting the setup each time.
- ChatbotA chatbot is software you converse with by typing or speaking. Older chatbots followed scripted decision trees; modern AI chatbots such as ChatGPT, Claude, Gemini, and Copilot use large language models to understand and respond to almost any request.