Reggae / Ska / Rocksteady
Reggae has two meanings. It is a generic name for all Jamaican popular music since 1960 —'West Indian style of music with a strongly accented subsidiary beat' according to the Concise Oxford Dictionary. But reggae can also refer to the particular beat that was popular in Jamaica from about 1969 to 1983.
Jamaican popular music since 1960 can be roughly divided into four eras each of which had a distinctive beat — ska, rocksteady, reggae, and dancehall. Ska dated from about 1960 to mid 1966. Rocksteady lasted from late 1966 to lace 1968. The popular beat from 1969 to about 1983 was named reggae and had two phases 'early reggae, from about 1969 to 1974, and 'roots reggae, from about 1975 to 1983.
From 1983 onwards the prevalent sound has been called dancehall. Just as the ska beat is different from the rock-steady beat, so is the dancehall beat different from the reggae beat. Outside of Jamaica dance-hall is often called 'lama' or 'dub', but in Jamaica 'dub' usually refers specifically to bass-heavy instrumentals created by mixing out other instru-ments and leaving the drum and bass only.