An LLM is a deep learning model trained on vast amounts of text data to understand and generate human language. GPT-4, Claude, Gemini, and Llama are all LLMs. They work by predicting the next token in a sequence, building fluent, contextually appropriate text one step at a time.
LLMs are the foundation of most modern AI products — from chatbots and writing assistants to code generation and data extraction. Their capabilities and limitations are shaped by training data, model size, and alignment techniques like RLHF. Understanding what an LLM can and cannot do reliably is the first step to building on top of one.