This review covers recent advancements in the physics of thin-film ferroelectric oxides, with a focus on aspects specific to ferroelectric thin films. It begins by discussing the current state of ferroelectric thin films in electronic devices, including their applications in memories, FETs, and DRAMs. The review then delves into the physics relevant to device performance and failure, such as switching mechanisms, electrical characterization, and device failure modes. The review also highlights the progress in first-principles modeling of ferroelectric thin films, emphasizing the importance of strain effects in determining the properties of epitaxial thin ferroelectric films. Additionally, it explores emerging possibilities in nanoscale ferroelectrics, particularly in non-conventional nanoscale geometries like ferroelectric nanotubes and self-patterned arrays. Key topics include the Ishibashi-Orihara model for domain nucleation and growth, the scaling of coercive fields with film thickness, and the mobility of domain walls. The review also discusses the challenges and solutions in measuring hysteresis loops, leakage currents, and dielectric permittivity in ferroelectric materials. Finally, it addresses the interpretation of dielectric permittivity data, considering contributions from depletion charges and domain wall pinning. The review concludes by emphasizing the importance of understanding the behavior of ferroelectric thin films at the atomic and electronic structure levels, as well as the role of computational electronic structure theory in advancing the field.This review covers recent advancements in the physics of thin-film ferroelectric oxides, with a focus on aspects specific to ferroelectric thin films. It begins by discussing the current state of ferroelectric thin films in electronic devices, including their applications in memories, FETs, and DRAMs. The review then delves into the physics relevant to device performance and failure, such as switching mechanisms, electrical characterization, and device failure modes. The review also highlights the progress in first-principles modeling of ferroelectric thin films, emphasizing the importance of strain effects in determining the properties of epitaxial thin ferroelectric films. Additionally, it explores emerging possibilities in nanoscale ferroelectrics, particularly in non-conventional nanoscale geometries like ferroelectric nanotubes and self-patterned arrays. Key topics include the Ishibashi-Orihara model for domain nucleation and growth, the scaling of coercive fields with film thickness, and the mobility of domain walls. The review also discusses the challenges and solutions in measuring hysteresis loops, leakage currents, and dielectric permittivity in ferroelectric materials. Finally, it addresses the interpretation of dielectric permittivity data, considering contributions from depletion charges and domain wall pinning. The review concludes by emphasizing the importance of understanding the behavior of ferroelectric thin films at the atomic and electronic structure levels, as well as the role of computational electronic structure theory in advancing the field.