Natural Language Processing (NLP) involves using computational techniques to analyze and understand human languages. Key techniques in NLP include sentiment analysis to classify emotions in text, text classification to categorize text into predefined tags or categories, and tokenization which breaks text into discrete words and punctuation. NLP is used to teach machines how to read and understand human languages by identifying relationships between words and entities. Other areas of NLP include parts of speech tagging, constituent structure analysis, and analysis of pronunciation, morphology, syntax, semantics, and pragmatics.