The document discusses chatbots, which are conversational agents that interact with users using natural language. It provides an overview of what chatbots are, their history from early systems like ELIZA, and how they work using pattern matching. The document also covers different approaches to chatbot design and various domains where chatbots can be applied, such as for entertainment, foreign language learning, and information retrieval. It concludes that chatbots are effective tools in several domains but cannot perfectly imitate human conversation.