This chapter provides an in-depth exploration of the physics underlying seismic wave propagation, which is fundamental to geophysical exploration and subsurface imaging. It begins with an introduction to seismic wave types—body waves (P-waves and S-waves) and surface waves (Rayleigh and Love waves)—and emphasizes their role in interpreting the Earth’s subsurface structures. The chapter discusses how seismic waves travel through Earth’s layers, influenced by properties like density and elasticity, which are key to seismic interpretation and resource exploration. The wave equation, governing seismic behavior, is examined along with factors like wave velocity, reflection, refraction, attenuation, dispersion, and seismic anisotropy. The elastic properties of rocks, including stress–strain relationships and key elastic moduli, are also covered to provide a thorough understanding of rock behavior under stress. Forward modeling is introduced as an essential tool in predicting seismic responses and designing effective surveys, with applications in oil and gas exploration, carbon capture, and reservoir management. The chapter concludes with a discussion on seismic interpretation, emphasizing the role of seismic attributes in building geological models and addressing uncertainties. By integrating theory and practice, this chapter offers a comprehensive understanding of seismic waves for students, researchers, and professionals, and highlights the need for continued innovation and collaboration in advancing seismic science for a sustainable energy future.