ATAC-seq (Assay for Transposase-Accessible Chromatin with high-throughput sequencing) is a new technology that utilizes DNA transposase (Tn5) to cut open DNA regions and combine with next-generation high-throughput sequencing technology to study chromatin openness. Compared with MNase-seq and DNase-seq traditionally used to study chromatin openness, ATAC-seq is the preferred method for chromatin accessibility due to its high repeatability, simple and time-saving experimental procedures and operations, and the ability to identify all open regions in the genome with only a small number of cells/tissues.