The brown booby is a large seabird of the booby family Sulidae, of which it is perhaps the most common and widespread species. It has a pantropical range, which overlaps with that of other booby species. The gregarious brown booby commutes and forages at low height over inshore waters. Flocks plunge-dive to take small fish, especially when these are driven near the surface by their predators. They nest only on the ground, and roost on solid objects rather than the water surface.

A booby is a seabird in the genus Sula, part of the family Sulidae. Boobies are closely related to the gannets (Morus), which were formerly included in Sula.