The primary objective of Artificial Intelligence (AI) is to empower computers to perform tasks necessitating intellectual capabilities. These tasks include complex decision-making and planning, vision or perception, and comprehending human language. Natural Language Processing (NLP) is an AI subfield dedicated to devising and implementing models, systems, and algorithms to tackle problems related to understanding human language, such as translation, question answering, and summarization. This chapter serves as an introductory guide to the essential tasks, methods, and challenges in NLP. It offers a concise overview of popular NLP tasks, accompanied by background information and terminology. The chapter discusses common evaluation methods and metrics, as well as a summary of state-of-the-art results across various key tasks. It then delves into a detailed examination of current NLP methods, with a focus on deep learning approaches. The chapter also presents a discussion on common-sense reasoning in NLP, including recent challenges and developed techniques.