OTU vs. Wayne graph (Venn graph, Venn graph, Weng graph, van der Waals graph) is a kind of sketch used to represent sets or classes in the non strict sense in the branch of set theory or class theory mathematics. Drawing experience: taxonomically, it can be divided into boundary, phylum, class, order, family, genus, species, as well as artificially defined OTU. At which level do we compare Venn maps. The principle of selection is to use OTU first. If there is no good overlap, it is likely to be the functional overlap at a higher level of classification, and try from the bottom up. Wayne diagram can be used to count the number of common and unique OTUs in multiple samples, which can intuitively show the similarity and overlap of OTUs in environmental samples.