A Large Language Model (LLM) is a deep learning model — typically with billions or trillions of parameters — trained on enormous amounts of text to predict the next token in a sequence. The major LLMs powering customer service AI in 2026 include Anthropic’s Claude family, OpenAI’s GPT family, Google’s Gemini, and various open-source alternatives (Llama, Mistral, Qwen).
LLMs handle the language understanding and generation that makes modern AI customer service work. In customer portal contexts, LLMs are typically paired with RAG to ground responses in your knowledge base rather than relying solely on the model’s training data.
See our AI customer service article.