The major fields mathematics is organized into, classified through the Mathematics Subject Classification (MSC2020), the scheme the American Mathematical Society and zbMATH jointly maintain and every research paper in the field is tagged against. Each branch here is a working discipline with its own journals, conferences and open problems. Belongs here: named branches such as Number Theory or Topology, grouped below into twelve subcategories following MSC2020's own ordering. Does not belong here: individual theorems, concepts or the mathematicians who work in a branch, each its own entity type.