The Bee Gees are a musical group that was originally made up of a singing trio of brothers — Barry, Robin, and Maurice Gibb. The trio were successful for most of their forty years of recording music, but they had two distinct periods of exceptional success: as a harmonic "soft rock" act in the late 1960s and early 1970s, and as the foremost stars of the disco music era in the late 1970s. The group sang three-part tight harmonies that were instantly recognisable; brother Robin's clear vibrato lead was a hallmark of their earlier hits, while Barry's R&B falsetto became a signature sound during the disco years. The brothers co-wrote all of their own hits, as well as writing and producing several major hits for other artists.