ChatGPT is a language model developed by OpenAI. It is a variant of the GPT (Generative Pretrained Transformer) architecture, which is a type of transformer-based neural network trained on a large corpus of text data. ChatGPT has been trained on a massive dataset to generate human-like text, making it capable of answering questions, generating conversation, composing poetry and more. It uses a combination of machine learning and deep learning techniques to process and generate text, and is capable of performing various language tasks with high accuracy.