GPT refers to a series of large language models developed by OpenAI that use the transformer architecture. They are 'generative' because they create new text, 'pre-trained' on a vast corpus of unlabeled data, and 'transformers' based on their underlying neural network structure.
Introduced by OpenAI in 2018 with the paper 'Improving Language Understanding by Generative Pre-Training'.
GPT-3 and subsequently ChatGPT popularized the term globally, making 'GPT' synonymous with advanced AI for the general public.