This chapter offers a comprehensive study of natural hazards and their transformation into disasters, providing an in-depth analysis of various types of hazards, their causes, and the resulting impacts on human societies, ecosystems, and infrastructure. This chapter explores four primary categories of natural hazards: geological, meteorological, hydrological, and biological. Each section highlights the characteristics and challenges of specific hazards such as earthquakes, hurricanes, floods, and pandemics, with particular attention to the role of human activities and climate change in exacerbating the frequency and severity of these events. Additionally, this chapter underscores the importance of early warning systems, preparedness, and risk management strategies in reducing disaster impacts and enhancing resilience. The global distribution and frequency of natural hazards are examined, emphasizing the significance of disaster preparedness, adaptive strategies, and the need for international cooperation in mitigating losses and promoting sustainable development in the face of growing environmental challenges. Furthermore, this chapter examines some of the most catastrophic natural disasters in history, such as the Yangtze River Flood (1931), the Haiti Earthquake (2010), and the eruption of Mount Tambora (1815), highlighting their profound effects on human societies and ecosystems.