Polydopamine (PD) is a versatile and simple surface functionalization method inspired by the adhesive properties of mussel adhesive proteins. Since its first report in 2007, PD has evolved into a powerful tool for modifying surfaces across various fields, including biomedical, energy, and consumer products. This review covers the current state of PD coating methods, the ongoing efforts to understand and tailor PD's complex structure and chemical properties, and emerging trends in PD research. Key advancements include the use of dopamine analogs, nitrogen-free polyphenolic precursors, and improvements in coating mechanical properties. PD coatings are known for their substrate versatility, ease of application, and the ability to form conformal thin films on a wide range of materials. The review also discusses the challenges and future opportunities in PD research, such as enhancing mechanical robustness and expanding the chemical and biological diversity of PD-like coatings.Polydopamine (PD) is a versatile and simple surface functionalization method inspired by the adhesive properties of mussel adhesive proteins. Since its first report in 2007, PD has evolved into a powerful tool for modifying surfaces across various fields, including biomedical, energy, and consumer products. This review covers the current state of PD coating methods, the ongoing efforts to understand and tailor PD's complex structure and chemical properties, and emerging trends in PD research. Key advancements include the use of dopamine analogs, nitrogen-free polyphenolic precursors, and improvements in coating mechanical properties. PD coatings are known for their substrate versatility, ease of application, and the ability to form conformal thin films on a wide range of materials. The review also discusses the challenges and future opportunities in PD research, such as enhancing mechanical robustness and expanding the chemical and biological diversity of PD-like coatings.