Epigenetics is the study of heritable phenotype changes that do not involve alterations to the primary DNA sequence. These modifications influence how genes are expressed, effectively determining which genes are active or silent within a cell. Mechanisms of epigenetic regulation include DNA methylation, where methyl groups are added to DNA bases, and histone modification, where chemical changes to histone proteins affect chromatin structure. These processes can compact or decompact the DNA, thereby regulating access to the genetic code. Understanding epigenetics is crucial for grasping how environmental factors, metabolic states, and developmental signals communicate with the genome to guide cell differentiation and maintain genomic stability throughout an organism's lifespan.