The King and I is a musical by Richard Rodgers and Oscar Hammerstein II. Its script is based on the book Anna and the King of Siam by Margaret Landon. The plot comes from the story written by Anna Leonowens, who became school teacher to the children of King Mongkut of Siam in the early 1860s. Leonowens' story, The English Governess at the Siamese Court, was autobiographical, although its objective accuracy is questionable; in Thailand, the possession of anything related to Anna and the King of Siam or The King and I is illegal, because of the historical inaccuracies about the King of Siam.

The musical opened on Broadway in 1951 and was the sixth collaboration for the team of Rodgers and Hammerstein. It ran for 1,246 performances, winning the Tony Award for Best Musical, among other awards. It spawned numerous revivals and a popular 1956 film version.

The best-known songs from the musical are probably "I Whistle a Happy Tune," "Getting to Know You," "Hello, Young Lovers," and "Shall We Dance?" The most colorful number in the musical, visually (to Western audiences), is the ballet "Small House of Uncle Thomas," choreographed by Jerome Robbins.

Rodgers and Hammerstein knew they were writing for stars — Gertrude Lawrence and Yul Brynner, the original Broadway leads — who were primarily actors rather than singers. Therefore, they reserved the sweeping, more challenging melodies for the characters of Tuptim and Lun Tha and kept the songs sung by the other leads simple.

Mary Martin, who had starred in South Pacific by Rodgers and Hammerstein a few years previously, was an investor in The King and I. When Gertrude Lawrence wanted to have a song with the children, Martin suggested that Rodgers and Hammerstein write new lyrics for "Suddenly Lovely," which had been cut out from South Pacific. The song then became "Getting to Know You."