This book consists of up-to-date information regarding the fundamentals and applications of Monte Carlo simulations. The aim of this book is to provide information about the current developments and applications of Monte Carlo Simulation (MCS) to the readers. The vital feature of the MCS method is random sampling. The book describes how such a sampling method can be used to resolve complex problems or evaluate complicated systems in distinct science and engineering domains. Issues like uncertainty assessment, statistical estimation, variance reduction and optimization have been described in this book. Recent applications of MCS are illustrated in estimation of transition behavior of organic molecules, particle diffusion, financial systems modeling, healthcare practices, chemical reaction and kinetic simulation of biological data and biophysics. Field-specific background knowledge and utilities of MCS have been discussed to optimize the accessibility of this book. This book aims at unifying knowledge of the concept from distinct areas to promote novel applications and research endeavors of MCS.