A song may be for a solo
singer, a
duet,
trio, or larger ensemble involving
more voices. Songs with more than one voice to a part are considered
choral works. Songs can be broadly divided into many different forms, depending on the criteria used. One division is between "
art songs", "
pop songs", and "
folk songs". Other common methods of
classification are by purpose (
sacred vs
secular), by
style (
dance,
ballad,
Lied, etc.), or by time of origin (
Renaissance,
Contemporary, etc.).
A song is a piece of music for accompanied or unaccompanied voice/voices or, "the act or art of singing," but the term is generally not used for large vocal forms including
operaand
oratorio.
[1] However, the term is, "often found in various figurative and transferred sense (e.g. for the lyrical second subject of a sonata...)." The noun "song" has the same etymological root as the verb "to sing" and the
Oxford English Dictionary (
OED) defines the word to mean "that which is sung" or "a musical composition suggestive of song." The OED also defines the word to mean "a poem" or "the musical phrases uttered by some birds, whales, and insects, typically forming a recognizable and repeated sequence and used chiefly for territorial defence or for attracting mates."

Bollywood songs, more formally known as
Hindi film songs, or
filmi songs are songs featured in
Bollywood films. Derided in Western film circles for the song-and-dance routine, Bollywood songs, along with dance, are a characteristic motif of Hindi cinema which gives it enduring popular appeal, cultural value and context. Hindi film songs form a predominant component of Indian pop music, and derives its inspiration from both classical and modern sources.
[1] Hindi film songs are now firmly embedded in North India's popular culture and routinely encountered in North India in marketplaces, shops, during bus and train journeys and numerous other situations. Though Hindi flms routinely contain many songs and some dance routines, there are not musicals in the Western theatrical sense; the music-song-dance aspect are an integral feature of the genre akin to plot, dialogue and other parameters.