Three extant subfamilies are recognized in the bear family Ursidae.
They are Ailuropodinae, which contains the giant panda; Tremarctinae, which contains the spectacled bear; and Ursinae, which contains the remaining living bears, including brown, polar, American black, Asian black, sloth, and sun bears. In the standard modern classification, these groups cover eight living species in five genera.
The arrangement reflects deep evolutionary relationships rather than simply body size, coat color, or geography. The giant panda is the sole living member of Ailuropodinae, while the spectacled bear is the sole living member of Tremarctinae. Ursinae is the most species-rich of the three extant subfamilies.
Ursidae has also included extinct subfamilies in broader historical classifications, including Agriotheriinae, Hemicyoninae, and Ursavinae. That is a common source of confusion: counting extinct as well as living lineages produces a larger number, but the question asks specifically for extant subfamilies.