Large language model (LLM) APIs from providers such as OpenAI, Azure OpenAI and AWS Bedrock let applications understand and generate text, extract structured data, call tools and work with images. They are consumed as cloud services, so there is no model to host or train.
Teams use LLM APIs to add capabilities that were impractical a few years ago: answering questions from documents, summarising, drafting and turning messy text into structured data. Doing it well is an engineering problem: grounding answers in your data, handling failures, testing quality and controlling cost.