In 1908, Camille Saint-Saëns composed the first music specifically for use in a motion picture (L'assasinat du duc de Guise), and releasing recordings of songs used in films became prevalent in the 1930s.
By convention, a soundtrack record can contain all kinds of music including music "inspired by" but not actually appearing in the movie; the score contains only music by the original film's composer(s) [REF].