A wide array of Nickel-Titanium instruments have been introduced for shaping root canals. Since there first appearance instrument design has changed considerably, progress has been made in manufacturing and also in alloy processing. All the file system have their benefits and weaknesses.The properties of an instrument is derived from the type of alloy used, degree of taper, cross-sectional design, etc. This book tries to give a comprehensive knowledge about different file systems used in Endodontics. It focuses on history, classification, material science, file and its different components, and newer advances in file system along with wide range of reviews. A list of references is also provided to encourage further reading. A deep understanding and love for the subject has been given into making of this book.