The Ensembl regulatory build (available for human and mouse) provides a set of regulatory features, sequences that may be implicated in gene regulation. These sequences have indicators suggesting they may be promoters, enhancers, or other elements. The features are based on regions of open chromatin identified using DNase I hypersensitivity assays, transcription factor binding sites, CTCF binding regions and histone modifications. These data come from experiments analysed by mainly ChIP-seq, but also DNase-seq experiments, from the ENCODE (Encyclopaedia of DNA elements), Blueprint and Roadmap Epigenomics projects. Ensembl displays the activity of these features in different cell types, and the evidence used to determine this activity.