Countdown is a song by American R&B singer Beyoncé Knowles from her fourth studio album 4?. It was written by Terius Nash, Shea Taylor, Knowles, Ester Dean, Cainon Lamb, Julie Frost, Michael Bivins, Nathan Morris and Wanya Morris. The songs development was motivated by the fact that Knowles wanted to create something refreshing and different by mixing several musical styles of the 1990s with the 1970s. Countdown serves as the albums official third single.

An American nuclear aircraft carrier and its crew are caught in a classic dilemma when a supernatural storm sends them back in time just before the Japanese assault on Pearl Harbour.