Bollywood song and dance

Bollywood film music is called filmi music (from Hindi, meaning "of films").
Songs from Bollywood movies are generally pre-recorded by professional playback singers, with the actors then lip synching the words to the song on-screen, often while dancing. While most actors, especially today, are excellent dancers, few are also singers. One notable exception was Kishore Kumar, who starred in several major films in the 1950s while also having a stellar career as a playback singer. K. L. Saigal, Suraiyya, and Noor Jehan were also known as both singers and actors. Some actors in the last thirty years have sung one or more songs themselves; for a list, see Singing actors and actresses in Indian cinema.
Playback singers are prominently featured in the opening credits and have their own fans who will go to an otherwise lackluster movie just to hear their favourites. Going by the quality as well as the quantity of the songs they rendered, most notable singers of Bollywood are Lata Mangeshkar, Asha Bhosle, Geeta Dutt, Shamshad Begum and Alka Yagnik among female playback singers; and K. L. Saigal, Talat Mahmood, Mukesh, Mohammed Rafi, Manna Dey, Hemant Kumar, Kishore Kumar, Kumar Sanu, Udit Narayan and Sonu Nigam among male playback singers. Mohammed Rafi is often considered arguably the finest of the singers that have lent their voice to Bollywood songs, followed by Lata Mangeshkar, who, through the course of a career spanning over six decades, has recorded thousands of songs for Indian movies. The composers of film music, known as music directors, are also well-known. Their songs can make or break a film and usually do. Remixing of film songs with modern beats and rhythms is a common occurrence today, and producers may even release remixed versions of some of their films' songs along with the films' regular soundtrack albums.

Bollywood dances usually follow songs
The dancing in Bollywood films, especially older ones, is primarily modelled on Indian dance: classical dance styles, dances of historic northern Indian courtesans (tawaif), or folk dances. In modern films, Indian dance elements often blend with Western dance styles (as seen on MTV or in Broadway musicals), though it is not unusual to see Western pop and pure classical dance numbers side by side in the same film. The hero or heroine will often perform with a troupe of supporting dancers. Many song-and-dance routines in Indian films feature unrealistically instantaneous shifts of location and/or changes of costume between verses of a song. If the hero and heroine dance and sing a pas-de-deux (a dance and ballet term, meaning "dance of two"), it is often staged in beautiful natural surroundings or architecturally grand settings. This staging is referred to as a "picturisation".
Songs typically comment on the action taking place in the movie, in several ways. Sometimes, a song is worked into the plot, so that a character has a reason to sing; other times, a song is an externalisation of a character's thoughts, or presages an event that has not occurred yet in the plot of the movie. In this case, the event is almost always two characters falling in love.
Bollywood films have always used what are now called "item numbers". A physically attractive female character (the "item girl"), often completely unrelated to the main cast and plot of the film, performs a catchy song and dance number in the film. In older films, the "item number" may be performed by a courtesan (tawaif) dancing for a rich client or as part of a cabaret show. The dancer Helen was famous for her cabaret numbers. In modern films, item numbers may be inserted as discotheque sequences, dancing at celebrations, or as stage shows.
For the last few decades Bollywood producers have been releasing the film's soundtrack, as tapes or CDs, before the main movie release, hoping that the music will pull audiences into the cinema later. Often the soundtrack is more popular than the movie. In the last few years some producers have also been releasing music videos, usually featuring a song from the film. However, some promotional videos feature a song which is not included in the movie.