NLP is a branch of artificial intelligence that enables more natural human-to-computer communication by bridging human and machine language. NLU is a subset of NLP that converts input text or speech into structured data to extract meaning, recognize entities, and extract information. NLG is another subcategory of NLP that constructs sentences based on a given semantic frame to explain structured data in meaningful sentences humans can understand. These concepts are applied in various use cases such as chatbots, sentiment analysis, automated ticketing support and routing, and automatic text summarization, enabling machines to understand and process natural language, generate responses, and provide actionable insights.