The field of photonic crystal fibers (PCFs) has witnessed significant advancements, leading to the development of various fiber types with unique properties. This book compiles doctoral theses, influential publications, and research works related to PCFs, offering a comprehensive overview of different fibertypes. Each chapter focuses on a specific PCF type, discussing the transmission of light in PCFs based on Maxwell's equations. Additionally, it covers in-depth studies on nonlinear effects, solitons, and supercontinuum generation. The book provides separate chapters dedicated to solid-core, liquid-core, and hollow-core PCFs, presenting a detailed analysis of their characteristics and applications.