Courtesy the ‘Hook, Line, and Sinker’ formula.

If you listen to the old Bollywood songs, you will find that they mostly had one melody/tempo/beat that played throughout (or varied slightly).

However, the latest popular songs usually have multiple rhythms, that vary drastically over the course of the song.

• The hook: The song starts off with a really simple tune that is easily recognizable. It could be anything – a looped auto-tune (the intro to Gangnam style), a really weird, wacko sound (the “Ew ew” (or something like that) part at he beginning of Baby Doll), or a catchphrase (“Humko kehte Superman, on karlo handycam” (Subah hone na de)).
• The line: This is the major part of the song. The remnant of the constant melody of the songs of yesteryear.
• The sinker: Finally, comes the last part. It could be a rap portion, a noticeable bass drop, a chorus part in a completely different tempo. It usually occurs around halfway into the song.

The sharp transitions in the tempo throughout the song ensures that you can’t really predict what’s coming next. The catchphrases are usually earworms that stick around in your head all day.