This review by Williams and Cieza provides an overview of protoplanetary disks and their evolution, focusing on observations of the outer parts of these disks beyond 1 AU. The authors discuss the formation, properties, and evolution of protoplanetary disks, emphasizing recent infrared and millimeter-wavelength observations. Key topics include the classification of young stellar objects, disk formation, disk properties such as mass, radius, structure, and composition, disk lifetimes, and disk evolution. The review highlights the importance of these disks in understanding exoplanet formation and the origins of the Solar System. It also addresses the challenges and future prospects in protoplanetary disk research, including the role of magnetic fields, disk instability, and the detection of large dust grains. The authors conclude with a summary of key points and future directions in the field.This review by Williams and Cieza provides an overview of protoplanetary disks and their evolution, focusing on observations of the outer parts of these disks beyond 1 AU. The authors discuss the formation, properties, and evolution of protoplanetary disks, emphasizing recent infrared and millimeter-wavelength observations. Key topics include the classification of young stellar objects, disk formation, disk properties such as mass, radius, structure, and composition, disk lifetimes, and disk evolution. The review highlights the importance of these disks in understanding exoplanet formation and the origins of the Solar System. It also addresses the challenges and future prospects in protoplanetary disk research, including the role of magnetic fields, disk instability, and the detection of large dust grains. The authors conclude with a summary of key points and future directions in the field.