The primary function of histones is to organize DNA within the cell nucleus by packaging it into compact structures called nucleosomes. Histones also play a fundamental role in the regulation of gene expression through their interaction with DNA. This is done through histone modification (a post-translational process) which increases gene expression. Histone modifications alter chromatin structure or recruit enzymes that modify histones, impacting the regulation of gene activity within cells. Histone modifications, such as acetylation, methylation, phosphorylation, ubiquitination, and others, can alter the interaction between histones and DNA, either compacting or loosening chromatin structure.