A large language model (LLM) is a type of artificial intelligence (AI) model trained on massive amounts of text data to understand, generate, and manipulate human language. These models use deep learning techniques, primarily based on transformers (e.g., GPT, BERT, LLaMA), to process and generate text in a way that mimics human writing and comprehension. A LLM is a type of foundation model -- a large-scale, pre-trained AI model that serves as a base for multiple downstream tasks.