  The analysis of biological sequencing data has been one of the biggest
applications of string algorithms. The approaches used in many such
applications are based on the analysis of k-mers, which are short fixed-length
strings present in a dataset. While these approaches are rather diverse,
storing and querying a k-mer set has emerged as a shared underlying component.
A set of k-mers has unique features and applications that, over the last ten
years, have resulted in many specialized approaches for its representation. In
this survey, we give a unified presentation and comparison of the data
structures that have been proposed to store and query a k-mer set. We hope this
survey will serve as a resource for researchers in the field as well as make
the area more accessible to researchers outside the field.
