who sang it?
American singer Madonna
Introduction
American singer Madonna 
what is into the groove? "Into the Groove" is a song
Madonna Madonna Madonna
Into the Groove Into the Groove Into the Groove
Introduction Introduction Introduction
"Into the Groove" is a song recorded by American singer Madonna for the 1985 film "Desperately Seeking Susan".  "Into the Groove" is a song recorded by American singer Madonna for the 1985 film "Desperately Seeking Susan".  "Into the Groove" is a song recorded by American singer Madonna for the 1985 film "Desperately Seeking Susan". 
wiki:12744913
Into the Groove [SEP] Introduction
"Into the Groove" is a song recorded by American singer Madonna for the 1985 film "Desperately Seeking Susan". It was featured on the re-issue of her second studio album, "Like a Virgin" (1984), outside North America. Sire Records released it on July 15, 1985, as the album's fourth single. Madonna's inspiration behind the song was the dance floor, and she wrote it while watching a handsome Puerto Rican man, across her balcony. Initially written for her friend Mark Kamins, Madonna later decided to use it as the soundtrack of the film "Desperately Seeking Susan". "Into the Groove" consists of instrumentation from synthesizers and drum machines.