Keys to Soil Taxonomy serves two purposes. It provides the taxonomic keys necessary for the classification of soils in a form that can be used easily in the field. It also acquaints users of the taxonomic system with recent changes in the system. The eleventh edition of the Keys to Soil Taxonomy incorporates all changes approved since the publication of the second edition of Soil Taxonomy: A Basic System of Soil Classification for Making and Interpreting Soil Surveys (1999). One of the most significant changes in the eleventh edition is the addition of the suborders Wassents and Wassists for subaqueous Entisols and Histosols.