At Bitesize Bio, James Hadfield gives an introduction to ChIP-seq for the uninitiated. Chromatin immunoprecipitation allows researchers to determine where protein-binding sites are located on DNA, and researchers coupled that approach to arrays, making ChIP-chip analyses. But, as Hadfield notes, "while this was a revolutionary approach, the technique is limited by the array technologies used." And so, chromatin immunoprecipitation was joined up with next-gen sequencing technologies.