Dialogues and lyrics

Film scripts (known as dialogues in Indian English) and their song lyrics are often written by different people. Scripts are usually written in an unadorned Hindustani, which would be understood by the largest possible audience. Bollywood films tend to use a colloquial register of Hindustani, mutually intelligible by Hindi and Urdu speakers. Most of the classic scriptwriters of what is known as Hindi cinema, including Salim–Javed, Gulzar, Rajinder Singh Bedi, Inder Raj Anand, Rahi Masoom Raza and Wajahat Mirza, primarily wrote in Urdu. Salim-Javed wrote in Urdu script, which was then transcribed by an assistant into Devanagari script so Hindi readers could read the Urdu dialogues. During the 1970s, the Urdu writers and screenwriters Krishan Chander and Ismat Chughtai said that "more than seventy-five per cent of films are made in Urdu" but were categorised as Hindi films by the government. Urdu poetry has strongly influenced Bollywood songs, whose lyrics also draw from the ghazal tradition (filmi-ghazal). According to Javed Akhtar in 1996, Urdu diction dominates Bollywood film dialogue and lyrics, with about 90% of them written in Urdu script, including his own works as well as those of Majrooh Sultanpuri and Anand Bakshi.

Some films have used regional dialects to evoke a village setting, or archaic Urdu in medieval historical films. In her book, The Cinematic ImagiNation, Jyotika Virdi wrote about the presence of Urdu in Hindi films: "Urdu is often used in film titles, screenplay, lyrics, the language of love, war, and martyrdom." Virdi notes that although Urdu was widely used in classic Hindi cinema decades after partition because it was widely taught in pre-partition India, its use has declined in modern Hindi cinema: "The extent of Urdu used in commercial Hindi cinema has not been stable ... the decline of Urdu is mirrored in Hindi films ... It is true that many Urdu words have survived and have become part of Hindi cinema's popular vocabulary. But that is as far as it goes ... For the most part, popular Hindi cinema has forsaken the florid Urdu that was part of its extravagance and retained a 'residual' Urdu". However, Urdu continues to be used in Bollywood films for dialogues and (particularly) songs.

Contemporary mainstream films also use English; according to the article "Bollywood Audiences Editorial", "English has begun to challenge the ideological work done by Urdu." Some film scripts are first written in Latin script. Characters may shift from one language to the other to evoke a particular atmosphere (for example, English in a business setting and Hindi in an informal one). The blend of Hindi, Urdu and English sometimes heard in modern Bollywood films, known as Hinglish, has become increasingly common.

Cinematic language (in dialogues or lyrics) is often melodramatic, invoking God, family, mother, duty, and self-sacrifice. Song lyrics are often about love. Bollywood song lyrics (especially in older films) frequently use the poetic vocabulary of court Urdu, with a number of Persian loanwords. Another source for love lyrics in films such as Jhanak Jhanak Payal Baje and Lagaan is the long Hindu tradition of poetry about the loves of Krishna, Radha, and the gopis.

Music directors often prefer working with certain lyricists, and the lyricist and composer may be seen as a team. This phenomenon has been compared to the pairs of American composers and songwriters who created classic Broadway musicals.