Biomechanical preparation is a crucial step of root canal therapy which involves preparation of root canal space before receiving the obturating material.Traditionally hand instruments have been used for the purpose but now a days rotary endodontic instruments are gaining popularity due to their improved cutting efficiency with enhanced mechanical properties.There are numerous rotary files available in the market including variety of systems from different manufacturers.This book is intended to give an insight to some of popular rotary file systems available in market along with fundamental concepts and design features.Basic metallurgy of rotary files and their evolution with time has also been covered.Comparative evaluation of various systems has also been tried based on the available studies.Readers will also get some brief ideas about some of popular endomotors available in market.