A tremendous amount of information regarding the nature and regulation of heterochromatin has emerged in the past 10 years. This rapid progress is largely due to the development of techniques such as chromatin immunoprecipitation or "ChIP," which allow analysis of chromatin structure. Further technological advances such as microarray analysis and, more recently, deep sequencing technologies, have made ChIP an even more powerful tool. ChIP allows the investigator to identify protein interactions and/or the presence of various chromatin modifications at specific genomic loci.