What is the purpose of DNA methylation?

DNA methylation is an epigenetic mechanism that regulates gene expression. By adding a methyl group to 5-carbon of cytosine, DNA methylation can recruit proteins involved in gene expression as well as repress transcription. It can also be used for long-term epigenetic silencing of X-linked genes, silencing retroviral elements, regulating tissue-specific-gene expression and genomic imprinting.