exact sequence variants should replace operational taxonomic units in markergene data analysis recent advances have made it possible to analyze highthroughput markergene sequencing data without resorting to the customary construction of molecular operational taxonomic units otus clusters of sequencing reads that differ by less than a fixed dissimilarity threshold new methods control errors sufficiently such that amplicon sequence variants asvs can be resolved exactly down to the level of singlenucleotide differences over the sequenced gene region the benefits of finer resolution are immediately apparent and arguments for asv methods have focused on their improved resolution less obvious but we believe more important are the broad benefits that derive from the status of asvs as consistent labels with intrinsic biological meaning identified independently from a reference database here we discuss how these features grant asvs the combined advantages of closedreference otusincluding computational costs that scale linearly with study size simple merging between independently processed data sets and forward predictionand of de novo otusincluding accurate measurement of diversity and applicability to communities lacking deep coverage in reference databases we argue that the improvements in reusability reproducibility and comprehensiveness are sufficiently great that asvs should replace otus as the standard unit of markergene analysis and reporting