Magma (from Greek μάγμα "paste") is a mixture of molten or semi molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in magma chambers that may feed a volcano or turn into a pluton. Magma is capable of intrusion into adjacent rocks, extrusion onto the surface as lava, and explosive ejection as tephra to form pyroclastic rock.

Magma is a complex high-temperature fluid substance. Temperatures of most magmas are in the range 700 °C to 1300 °C (or 1300 °F to 2400 °F), but very rare carbonatite melts may be as cool as 600 °C, and komatiite melts may have been as hot as 1600 °C. Most are silicate mixtures.

Environments of magma formation and compositions are commonly correlated. Environments include subduction zones, continental rift zones,mid-ocean ridges and hot spots. Despite being found in such widespread locales, the bulk of the Earth's crust and mantle is not molten. Rather, most of the Earth takes the form of a rheid, a form of solid that can move or deform under pressure. Magma, as liquid, preferentially forms in high temperature, low pressure environments within several kilometers of the Earth's surface.

Jannick Top is a French bass player and composer, born in Marseille. Top plays the electric bass and the cello.

In the 1970s, he was a lead member of the influential zeuhl band Magma, along with Christian Vander and Didier Lockwood. In 1977-1980 he played in the popular electronic project Space.

Since then, he has worked with many other musicians, including session work for Michel Berger, France Gall, Richard Cocciante, Bonnie Tyler, Eurythmics, Ray Charles, Céline Dion as well as live playing and musical direction for spectacles, including Johnny Hallyday and Starmania. In association with Serge Perathoner, keyboardist, he has also done a variety of film and advertisement musics.