Fibers are a class of materials characterized by a high aspect ratio, meaning they are significantly longer than they are wide, existing as continuous filaments or discrete elongated pieces. Within materials science, fibers are studied for their unique properties, which are heavily influenced by their molecular structure and orientation, and are broadly categorized as natural (e.g., cellulose, silk) or synthetic (e.g., polymer, glass, carbon). The applied science of fibers involves engineering their mechanical, thermal, and optical characteristics for a vast array of applications, ranging from traditional textiles and ropes to advanced technologies such as high-strength composites for aerospace, optical waveguides for telecommunications, and biocompatible scaffolds for tissue engineering.