Natural language understanding (NLU) is the subfield of natural language processing focused specifically on interpreting meaning and intent, rather than just processing the surface structure of text. Where NLP broadly covers understanding, generating, and manipulating language, NLU narrows in on the comprehension side: figuring out what a sentence actually means, including implied context, sentiment, and the speaker's underlying intent, even when the wording is ambiguous, informal, or grammatically imperfect.
This matters directly for anything that needs to act on what a person says rather than just recognize words: a voice assistant needs NLU to tell "book me a flight to Paris" apart from a casual mention of Paris in conversation, and a customer service chatbot needs it to distinguish a genuine complaint from a sarcastic remark, even when both use similar vocabulary.
