A descarga (literally discharge in Spanish) is an improvised jam session consisting of variations on Cuban music themes, primarily son montuno, but also guajira, bolero, guaracha and rumba. The genre is strongly influenced by jazz and it was developed in Havana during the 1950s. Important figures in the emergence of the genre were Cachao, Julio Gutiérrez, Bebo Valdés, Peruchín and Niño Rivera in Cuba, and Tito Puente, Machito and Mario Bauzá in New York. Originally, descargas were promoted by record companies such as Panart, Maype and Gema under the label Cuban jam sessions. From the 1960s, the descarga format was usually adapted by large salsa ensembles, most notably the Fania All-Stars. History Origins: son, filin and jazz During the 1940s, the term descarga was commonly used in the music scenes of Cuba to refer to performances of jazz-influenced boleros in an improvised manner. This was part of the so-called filin (feeling) movement spearheaded by artists such as José Antonio Méndez, César Portillo de la Luz, and Luis Yánez. This style was inherited by musicians such as Bebo Valdés and Frank Emilio Flynn who explored the combination of jazz and Cuban forms into the 1950s. In particular, Bebo's 1952 session with producer Norman Granz in Havana, credited to Andre's All Stars, is often cited as a milestone in the development of Cuban jazz, and by extension, descarga. At this time, however, the term descarga began to be used in a different way to describe jam sessions based on the son montuno and other Afro-Cuban rhythms. The incipient mambo and Afro-Cuban jazz scene found in New York during the 1940s was also a catalyst of the development of descargas, with artists such as Machito, Dizzy Gillespie, Charlie Parker and Tito Puente performing extended jams with Afro-Cuban motifs. 1950s: the Panart sessions The first series of commercially successful descarga jam sessions were recorded mostly between 1956 and 1958 at the Panart studios in Havana. The Panart descarga sessions were released in three volumes under the title Cuban Jam Session; they would sell over a million copies. Volumes I (1956, yellow cover) and II (1957, blue cover) were recorded under the direction of Julio Gutiérrez with Peruchín on piano. The sessions were recorded by engineer Fernando Blanco in Havana and then sent for editing to New York. According to the original liner notes of Volume I, the studio doors were opened at 10:30 pm