This lecture covers the fundamentals of surface plasmon polaritons (SPP) on metal surfaces, discussing topics such as SPP dispersion relations, Maxwell's equations at interfaces, and complex propagation vectors. The instructor references key works in the field and explains the behavior of SPP modes in different scenarios, including semi-infinite metals and Drude metals in air. The lecture also explores the localization of charges along metal surfaces and the impact of dielectric functions on SPP dispersion. Practical applications and experimental observations related to SPP coupling and field distribution are presented, providing a comprehensive overview of the field.