Histone deacetylases (HDACs) are enzymes that play a crucial role in regulating gene expression by removing acetyl groups from histones, the proteins around which DNA is wrapped. This process leads to a more compact and inactive form of DNA, making it less accessible for transcription. By influencing the structure of chromatin, HDACs can turn genes on or off, impacting various cellular functions. HDACs are involved in several biological processes, including cell cycle regulation, differentiation, and apoptosis. They have also been implicated in various diseases, such as cancer and neurodegenerative disorders, making them potential targets for therapeutic interventions.