Histone modification refers to the chemical changes made to the proteins called histones that help package and organize DNA in the cell nucleus. These modifications can include the addition or removal of various chemical groups, such as methyl or acetyl groups, which can influence how tightly or loosely the DNA is wrapped around the histones. This, in turn, affects gene expression and the accessibility of DNA for processes like transcription. These modifications play a crucial role in regulating cellular functions and can be inherited through cell divisions. They are part of a broader field known as epigenetics, which studies how environmental factors can influence gene activity without altering the underlying DNA sequence. Understanding histone modification is essential for insights into development, disease, and potential therapeutic approaches.