1. Epigenetics refers to heritable changes in gene expression that do not involve changes to the underlying DNA sequence. 2. Important epigenetic mechanisms include DNA methylation, histone modification, and microRNA involvement. These mechanisms play roles in normal development and cell differentiation. 3. Epigenetic changes can be influenced by environmental factors and behaviors. They also contribute to genomic imprinting and X-chromosome inactivation. 4. Abnormal epigenetic patterns are implicated in cancer development. Targeting epigenetic alterations offers potential for new cancer interventions.