Histones are proteins found in the cell nucleus that play a crucial role in organizing and packaging DNA. They help form a structure called nucleosomes, where DNA wraps around histones, allowing it to fit within the cell. This organization is essential for DNA replication and gene expression. Histones can undergo various chemical modifications, which can influence how tightly or loosely DNA is wrapped around them. These modifications affect gene accessibility and activity, playing a key role in epigenetics, the study of changes in gene expression that do not involve alterations to the underlying DNA sequence.