A real number ring is a ring whose elements are real numbers of variable precision.
The object RealField is a type, with ancestor classes InexactField < EngineRing < Ring < Type < MutableHashTable < HashTable < Thing.
The source of this document is in /build/reproducible-path/macaulay2-1.25.05+ds/M2/Macaulay2/packages/Macaulay2Doc/doc_rings.m2:452:0.