In this chapter, we will understand that the regulatory regions of a gene, such as promoters and enhancers, must be located within accessible chromatin to start transcription. Chromatin is the physical manifestation of epigenetics. In a tissue- and cell type-specific manner, the majority of the genome is buried in heterochromatin, with only approximately half of all genes being actively transcribed. Nutritional epigenetics, a subdiscipline of nutrigenomics, examines how dietary compounds influence the epigenome. Various epigenetic mechanisms, such as posttranslational histone modifications and DNA methylation, process information provided by dietary molecules. Many chromatin-modifying enzymes use intermediary metabolites as cosubstrates and/or cofactors. We will also discuss the memory function of the epigenome in both somatic and germ cells, the latter forming the basis for transgenerational inheritance. Different types of human cohorts and “natural experiments” enable the study of epigenetics at a population level. This research provides a foundation for understanding the process of epigenetic programming of cells and tissues.