The recent developments in epigenetics have shown a very important role of epigenetic changes in cancer initiation, development, and progression. Some of the important histone modifications shown to occur are methylation, acetylation, phosphorylation, citrullination, sumoylation, ADP ribosylation, deamination, ubiquitination, formylation, O-GlcNAcylation, propionylation, butyrylation, proline isomerization, and crotonylation but most of the studies in past had limited their studies mainly on histone methylation, acetylation, and phosphorylation. Modification of DNA strand by hypermethylation and hypomethylation regulates genomic instability and promotes cancer.