Epigenetics is a branch of biology which deals with the study of heritable phenotype changes that are not associated with the alterations in the DNA sequence. It generally involves the alterations which affect gene expression and activity but it may also include any heritable phenotypic change. These effects on cellular and physiological phenotypic characteristics may be a part of normal development or may result from environmental factors. Epigenomics refers to the study of the epigenome which is the complete set of epigenetic modifications taking place in the genetic material of a cell. These epigenetic modifications are reversible in nature. They affect gene expression without altering the DNA sequence. The book studies, analyses and upholds the pillars of epigenetics and epigenomics and their utmost significance in modern times. It consists of contributions made by international experts. As these fields are emerging at a fast pace, this book will help the readers to better understand their concepts.