“Send In the Clowns” is a song written by Stephen Sondheim for the 1973 musical A Little Night Music, an adaptation of Ingmar Bergman‘s 1955 film Smiles of a Summer Night. It is a ballad from Act Two, in which the character Desirée reflects on the ironies and disappointments of her life. Among other things, she looks back on an affair years earlier with the lawyer Fredrik, who was deeply in love with her, but whose marriage proposals she had rejected. Meeting him after so long, she realizes she is in love with him and finally ready to marry him, but now it is he who rejects her: He is in an unconsummated marriage with a much younger woman. Desirée proposes marriage to rescue him from this situation, but he declines, citing his dedication to his bride. Reacting to his rejection, Desirée sings this song. 

Sondheim explained in a 1990 interview:

I get a lot of letters over the years asking what the title means and what the song’s about; I never thought it would be in any way esoteric. I wanted to use theatrical imagery in the song, because she’s an actress, but it’s not supposed to be a circus […] It’s a theater reference meaning “if the show isn’t going well, let’s send in the clowns”; in other words, “let’s do the jokes.” I always want to know, when I’m writing a song, what the end is going to be, so “Send in the Clowns” didn’t settle in until I got the notion, “Don’t bother, they’re here”, which means that “We are the fools.”

In a 2008 interview, Sondheim further clarified:

As I think of it now, the song could have been called “Send in the Fools”. I knew I was writing a song in which Desirée is saying, “aren’t we foolish” or “aren’t we fools?” Well, a synonym for fools is clowns, but “Send in the Fools” doesn’t have the same ring to it.

“Send in the Clowns” was never meant to be a soaring ballad; it’s a song of regret. And it’s a song of a lady who is too upset and too angry to speak…