The theme was composed by Argentine musician Lalo Schifrin for the original Mission: Impossible television series, which premiered in 1966. Its 5/4 time signature was inspired by Morse code for the letters M and I, giving it that distinctive long-long-short-short pulse. The music later became inseparable from the long-running film series starring Tom Cruise, which began in 1996 and reused and reworked Schifrin's motif. Online, the full version spread as the go-to shorthand for any stealthy, high-stakes or overly dramatic mission, serious or parody.