Eukaryotic genomes are ubiquitously associated into chromatin; however, cells must spatially and temporally regulate specific loci independently of bulk chromatin. In order to achieve the high level of control required to co-ordinate nuclear processes such as DNA replication, repair, and transcription, cells have developed a variety of means to locally and specifically modulate chromatin structure and function. This can involve covalent modification of histones, the incorporation of histone variants, and non-covalent remodelling by ATP-dependent remodeling enzymes.