Histone H4 is one of the four core histones (H2A, H2B, H3, and H4) essential for the formation of nucleosomes, which are fundamental units of chromatin structure in eukaryotic cells. Histone H4 plays a crucial role in the regulation of gene expression and chromatin dynamics. Histone H4, along with the other core histones, helps package DNA into nucleosome particles, facilitating the organization of chromosomal fiber and regulating gene expression. The histone H4 protein undergoes various post-translational modifications, including methylation, acetylation, phosphorylation, and ubiquitination, which are crucial for the regulation of chromatin dynamics, DNA repair, and transcription.