The GPTGenerative Pre-trained Transformer — OpenAI's family of large language models from GPT-1 through GPT-5.-3 APIApplication programming interface — a defined way for programs to talk to each other or to a service. let apps call a 175B-parameter model for completion, summarization, and code generation via HTTPHyperText Transfer Protocol — the protocol browsers use to request and receive web pages.. It launched the LLMLarge language model — a neural network trained on vast text to generate and reason about language. APIApplication programming interface — a defined way for programs to talk to each other or to a service. economy — copywriting tools, coding assistants, and chatbots built on a single endpoint before ChatGPTOpenAI's conversational chat product — brought large language models to hundreds of millions of users.'s consumer interface.

The GPTGenerative Pre-trained Transformer — OpenAI's family of large language models from GPT-1 through GPT-5.-3 APIApplication programming interface — a defined way for programs to talk to each other or to a service. was the commercial inflection point for LLMs in production software.

It proved developers would pay per token for generative AIModels that create new content — text, images, audio, or code — from learned patterns. at scale.