Los 40 (The 40, stylized as LOS40 and formerly Los 40 Principales, ) is a Top 40 music radio network and radio station brand in many Spanish-speaking countries from PRISA Radio. The station has its origins as a music show at Radio Madrid, today Cadena SER in 1966, where the 40 Principales chart was born, then evolved into a standalone radio station in 1979. LOS40 is the number one music station in most of the regions it serves. Some stations under this brand name are owned and operated or are licensed by PRISA to use the brand. Some LOS40 stations are operated by a local broadcasting company and affiliated with the company that holds a license to use the brand from Grupo PRISA. Each LOS40 network typically broadcasts its own national feed from its respective country. LOS40 stations broadcast in: Most LOS40 networks generally air Spanish and English contemporary hit music that mostly includes American, Latin American, Pan-European and British singers and bands. Most stations emphasize Latin Top 40 music; however Mexico and Panama stations feature more European and English-language music whilst Chile and Costa Rica stations plays more reggaeton and bachata. It has a high-rotation playlist consisting mainly of tracks from its private chart. The main music genres that can be heard are pop, pop-rock and some dance music from the '90s, '00s and present day. Countries where it previously had a presence: Colombia: As of 1 July 2020, the Caracol Radio directive belonging to the PRISA group due to temporary issues replaces LOS40 Colombia with Oxygen by LOS40 station of 'Urbano' format under the musical genres of reggaeton, bachata and electrónica. Nicaragua: Replaced by La Buenísima. Paraguay: Replaced by an evangelic radio station. History In 1965, the Ministry of Information and Tourism passed a law forcing medium wave radio stations to launch FM stations to develop FM in Spain. Due to the high costs of producing new shows, most of the schedule for the new stations was based on music, mainly classical music. In 1966, Cadena SER asked one of its broadcasters, Rafael Revert, to develop a new music show aimed at a younger audience. So he took the idea of the Top 40 and created a chart with the 40 top singles of the week, which would be voted on by the audience. So, on 18 July 1966, the first show of Los 40 Principales was broadcast