With the rise in train speeds, axle loads, and traffic density along with the broader engineering applications of new vehicles and track structures, the vehicle-track interaction has grown increasingly complex. Consequently, train safety and stability are more significantly influenced by elevated dynamic stresses. High-Speed Railway Track Dynamics provides a robust foundation for studying the intricate wheel-rail relationship and interaction mechanisms, offering critical insights for optimizing vehicle and track structure design. This chapter reviews recent advancements in track dynamics modeling and analytical methods while introducing key aspects of track dynamics analysis. Additionally, it evaluates relevant standards and limits, including safety and stability criteria for high-speed trains, track maintenance and management standards for high-speed railways, environmental noise and vibration regulations for rail transit, and vibration thresholds for historic building structures.