"Who's on First?" is a comedy routine made famous by Abbott and Costello. The premise of the sketch is that Abbott is identifying the players on a baseball team for Costello, but their names and nicknames can be interpreted as non-responsive answers to Costello's questions.
In February 1938, Abbott and Costello joined the cast of The Kate Smith Hour radio program, and the sketch was first performed for a national radio audience that March. Abbott and Costello performed "Who's on First?" numerous times in their careers, rarely performing it exactly the same way twice. They did the routine for President Franklin Roosevelt several times. An abridged version was featured in the team's 1940 film debut, One Night in the Tropics. The duo reprised the bit in their 1945 film The Naughty Nineties, and it is that longer version which is considered their finest recorded rendition. They also performed "Who's on First?" numerous times on radio and television (notably in The Abbott and Costello Show episode "The Actor's Home", widely considered the definitive version).
