Natural Language Processing (NLP) is a subfield of AI that focuses on the interaction between computers and human language, utilizing linguistics, computer science, and machine learning. Key techniques include tokenization, part-of-speech tagging, and named entity recognition, with applications ranging from chatbots to sentiment analysis. The field faces challenges such as language ambiguity and varying expressions, but advancements like transformer architecture and pre-trained models are enhancing its capabilities and future trends indicate a focus on ethical considerations and integration of multimodal data.