"Countdown" is a hardbop[1][2][3][4] jazz standard composed by American jazz saxophonist John Coltrane that was first featured on his fifth studio album, Giant Steps, in 1960.
The song is a contrafact of Miles Davis's "Tune Up", which is reharmonized to the Coltrane changes.
[3][5] The original recording has been described as having "resolute intensity .
[that] does more to modernize jazz in 141 seconds than many artists do in their entire careers".
This dominant 7 chord resolves in a V-I manner—F7 to B♭Δ7.