Urbanization has dramatically transformed human societies over the past century. Cities now accommodate over half of the global population, driving economic growth, technological innovation, and cultural exchange. However, rapid urban expansion often leads to environmental degradation, social inequality, and inadequate infrastructure. Air pollution, traffic congestion, and loss of green spaces are persistent challenges. Urban planners are increasingly adopting sustainable practices, such as green buildings, renewable energy integration, and efficient public transportation systems, to mitigate these effects. Social policies aimed at affordable housing, education, and healthcare are also essential for equitable urban development. Understanding the balance between economic growth and environmental and social sustainability is critical for shaping the cities of the future.