Histone Acetyltransferases (HATs) are enzymes that play a crucial role in the regulation of gene expression. They add acetyl groups to histones, which are proteins that help package DNA into a compact structure called chromatin. This acetylation process typically leads to a more relaxed chromatin structure, making it easier for transcription factors to access DNA and promote gene activation. The activity of HATs is essential for various cellular processes, including cell differentiation and response to external signals. Dysregulation of HATs can contribute to various diseases, including cancer, by altering gene expression patterns. Understanding HATs is vital for developing potential therapeutic strategies.