Heterobasidiomycetes, including jelly fungi, smuts and rusts, are basidiomycetes with septate basidia. This contrasts them to homobasidiomycetes, including most mushrooms and other Agaricomycetes, which have aseptate basidia. The division of all basidiomycetes between these two groups has been influential in fungal taxonomy, and is still used informally, but it is no longer the basis of formal classification. In modern taxonomy homobasidiomycetes roughly correspond to the monophyletic class Agaricomycetes, whereas heterobasidiomycetes are paraphyletic and as such correspond to various taxa from different taxonomic ranks, including the Basidiomycota other than Agaricomycetes and a few basal groups within Agaricomycetes.

Basidiomycota is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basidiomycota includes these groups: agarics, puffballs, stinkhorns, bracket fungi, other polypores, jelly fungi, boletes, chanterelles, earth stars, smuts, bunts, rusts, mirror yeasts, and Cryptococcus, the human pathogenic yeast.