Histones are alkaline (basic pH) proteins. They are found inside the nucleus of eukaryotic cells. Their purpose is to package DNA into structural units called nucleosomes.They are the main proteins in chromatin (a combination of DNA and protein), which makes up the contents of a cell nucleus.2A, H2B, H3, and H4 are the core histones, and H1 and H5 are the linker histones. The core histones form the center of the nucleosome, hence the term 'core'. The linker histones are found at the entrance and exit sites of the nucleosome and lock the DNA in place, hence the term 'linker'.