Hear what Wiki sayeth:
Westerners would tend to classify most Bollywood films as musicals, because few movies are made without at least one song-and-dance number. The standard Bollywood movie is expected to contain a number of elements, and one of the essentials is catchy music in the form of song-and-dance numbers woven into the script. Indeed, a movie's music is often released before the movie itself and helps increase the audience. However the term "musical" is misleading because songs in Bollywood movies are done with professional playback singers, electronic instrumentation, and world-class musical composition.