Overview
"Smile" is a song based on the theme song used in the soundtrack for Charlie Chaplin's 1936 film Modern Times.
Final sequence : https://www.youtube.com/watch?v=XjwqDFeCMnM
Background
Chaplin, who composed the song, was inspired by Puccini's Tosca. John Turner and Geoffrey Parsons added the lyrics and title in 1954. In the lyrics, based on lines and themes from the film, the singer is telling the listener to cheer up and that there is always a bright tomorrow, just as long as they smile.
"Smile" has become a popular standard since its original use in Chaplin's film and has been recorded by numerous artists.
From Wikipedia (CC BY-SA 4.0).