A Generative Pretrained Transformer, or GPT, is a type of artificial intelligence model known as a transformer. The "generative" part of the name refers to the model's ability to generate outputs, like sentences, based on the inputs it receives.

A "transformer" is a specific type of machine learning model that uses self-attention mechanisms to better understand the context of words in a sentence. This allows it to generate more accurate and contextually appropriate responses. It's particularly effective for tasks involving natural language processing, which is the technology used to enable machines to understand and respond to human language.

The "pretrained" part of the name refers to the method of training the model. Before it's used for a specific task, the model is trained on a large corpus of text data from the internet. This allows it to learn language patterns, grammar, facts about the world, and even some level of reasoning. However, it's worth noting that the model doesn't understand text in the way humans do. Instead, it learns to predict the next word in a sentence based on the words it has seen so far.

So, in essence, GPT is a type of AI model that can generate human-like text, having learned language patterns from a large dataset. It's especially adept at tasks involving language, making it a powerful tool in a variety of applications.