In this chapter, we delve into the critical role that natural language understanding (NLU) plays in shaping the future of artificial intelligence (AI). To set the stage, we begin by defining what constitutes an NLU system. Next, we explore how NLU can drive the evolution of next-generation AI systems, which promise to be more reliable, responsible, and personalized. To this end, we introduce the seven pillars for the future of AI, which represent the foundational elements necessary to advance AI technology in a way that is more transparent and reliable. Next, we propose the concept of responsible recommender systems, which incorporate ethical guidelines and user-centric principles to ensure recommendations are not only relevant but also fair, unbiased, and respectful of user privacy. Lastly, we present a framework for personalized sentiment analysis, which aims at making AI systems more responsive and attuned to the needs and emotions of each user.