This book is about a Quantum mechanical phenomena called '' tunnelling '' and how to account it role in biochemistry,reaction mechanism,nanotechnology,semiconductor and superconductor .in this book all these research area demonstrated in deep and trying to explore more possibilities for the further research. modern technique are introduced for the detection and traces of tunnelling effect . this book deals with electron tunnelling as well as tunnelling of molecule .this book delivered all way of fundamental mechanistic part and elaborating the inner process of tunnelling specially in bio-molecules and in conductors . application part of tunnelling in semiconductor and superconductor having a special set-up to demonstrate how quantum chemistry affecting in electronics . we are trying to report here the most relevantly part of tunneling through wave mechanism .