The rosids are members of a large clade of flowering plants, containing about 70,000 species, more than a quarter of all angiosperms.

Under the International Code of Nomenclature for algae, fungi, and plants (ICN), Rosidae is a botanical name at the rank of subclass. Circumscription of the subclass will vary with the taxonomic system being used; the only requirement being that it includes the family Rosaceae.