A chatbot is a software application that simulates conversation with users, typically through text, by generating responses using natural language processing and sometimes large language models. Early chatbots followed rigid scripts; modern ones powered by LLMs can handle open-ended questions, remember context within a session, and invoke external tools. Businesses use chatbots for 24/7 customer support, lead qualification, and internal helpdesks, though human handoff remains essential for complex or sensitive issues.