ChatGPT is a pre-trained language model developed by OpenAI that is trained to generate human-like text. It is based on the GPT (Generative Pre-trained Transformer) architecture, which is a type of transformer-based neural network. ChatGPT is trained on a large corpus of text data, such as books and articles, and is able to generate new text that is similar to the text it was trained on. It can be fine-tuned on specific tasks, such as language translation or question answering, by training it on smaller amounts of task-specific data. It can also be used as a general-purpose language model for tasks such as text generation and language understanding.