I Love Lucy premiered on American television in 1951, starring Lucille Ball and Desi Arnaz as Lucy and Ricky Ricardo, and ran for six seasons, becoming one of the most influential sitcoms ever made. Its cheerful instrumental theme, heard at the start of every episode, became inseparable from the show's image of domestic comedy and slapstick. Decades of reruns, syndication and clips shared online have kept the melody instantly recognisable, and creators still use it today to signal vintage television, wholesome mischief and a simpler era of comedy.