Methylation is a biological process that involves the addition of a methyl group (-CH3) to a molecule, typically DNA, RNA, or proteins. In the context of DNA, methylation refers to the addition of a methyl group to a cytosine base in a DNA sequence, which can regulate gene expression and chromatin structure. Aberrant DNA methylation patterns have been associated with various diseases, including cancer, neurological disorders, and autoimmune conditions. Research in the field of methylation aims to understand the mechanisms and implications of methylation in normal physiological processes and disease states, as well as to develop potential therapeutic interventions targeting methylation patterns.