In 1958, the actress Helen Jairag Richardson, better known by her screen name Helen, performed Bollywood's first "item song", the now well-known Mera Naam Chin Chin Chu, in the film Howrah Bridge. Since then, the Hindi film industry has showcased thousands of item numbers - highly choreographed, titillating performances to a catchy song - that have no bearing on the films in which they appear, being only a marketing tool to attract audiences.
"Katrina Kaif is an excellent example of someone who attracts a large number of people to a film when she does an item number," says Sunny D, a guitarist for the UK-based Asian band The 107, and an avid Bollywood fan.
Although Kaif's 2010 comedy Tees Maar Khan did not do well at the box office, her song Sheila Ki Jawani was a big hit in record stores, on the radio and among web downloads. In fact, the performance gained more awards than the film itself, including a Zee Cine Award for best choreography.
"Even if her fans are not interested in the film, they will go to see it for her performance," says D.
The trend has lent big support to Hindi films, according to Jasleen Bhambra, a professional Indian dancer based in London: item numbers attract more viewers, leading to high ticket sales, which translate into enormous earnings for the producers and studios, who then invest in new projects.
"Bollywood really is all about music, so what better way than to market a film with a song that people can't get out of their heads? Pair the song with an attractive girl, and the film is a winner," says Bhambra. "My favourite is the actress Malaika Arora Khan in the song Munni Badnam Hui from the Salman Khan-starrer Dabangg."
In the 1980s and 1990s, item numbers were seen as a way for newcomers to break into the film industry. The past decade, however, has seen even established actresses, such as Kareena Kapoor (Ra One, 2011) and Vidya Balan (Ferrari Ki Sawaari, 2012), taking advantage of the trend's capability to catapult their careers to great heights.
A-list actresses are paid large amounts of money to perform such sequences, especially since the producers regard them as an "investment". Mallika Sherawat admitted to receiving 10 million rupees (Dh660,000) to dance to the song Kalasala Kalasala in the 2011 film Osthi, a Tamil remake of Dabangg.
"Besides the monetary gain, it keeps these actresses in the public eye and in directors' minds [for future projects]," D explains.
Item numbers have also long been a target of controversy. When Helen's performance premiered in theatres, both the actress and the film producers were criticised for supposedly objectifying women. In recent years, similar criticism has been directed at several films with raunchy item numbers.
"But these songs are slowly becoming more about the music and the choreography and less about the girl," says Bhambra.
In the past decade, male actors have also made appearances in item songs, including Shah Rukh Khan (Kaal, 2005) and Hrithik Roshan (Krazzy 4, 2008).
"Performing an item number helps the actors to stay current, although sometimes many of the top stars do it as a favour to the directors," says D. "I watched Kaal only because Shah Rukh Khan did an item number in it. So these songs obviously are doing what they are meant to."
Three memorable item songs
Chaiyya Chaiyya – Dil Se (1998)
This was Malaika Arora Khan's item song debut, composed by A R Rahman. In 2003, the BBC conducted an international poll to choose the 10 most popular songs of all time – Chaiyya Chaiyya ranked ninth.
Kajra Re – Bunty Aur Babli (2005)
Aishwarya Rai did this item number to promote the comedy starring the father-son duo Amitabh and Abhishek Bachchan (who she married two years later). The film went on to become one of the biggest blockbuster hits that year. The song won two Filmfare awards, among others.
Sheila Ki Jawani – Tees Maar Khan (2010)
Featuring Katrina Kaif and choreographed by Farah Khan, the song took the industry by storm and is considered to be one of the most popular item numbers in recent years. With its catchy tune and glamorous costumes, it was such a huge hit that it outshone the movie, and went on to scoop up a few awards, too.