Tosca is an opera in three acts by Giacomo Puccini to an Italian libretto by Luigi Illica and Giuseppe Giacosa. It premiered at the Teatro Costanzi in Rome on January 14, 1900. The work, based on Victorien Sardou's 1887 French-language dramatic play, La Tosca, is a melodramatic piece set in Rome in June 1800, with the Kingdom of Naples's control of Rome threatened by Napoleon's invasion of Italy. It contains depictions of torture, murder and suicide, as well as some of Puccini's best-known lyrical arias, and has inspired memorable performances from many of opera's leading singers.

Puccini saw Sardou's play when it was touring Italy in 1889 and, after some vacillation, obtained the rights to turn the work into an opera in 1895. Turning the wordy French play into a succinct Italian opera took four years, during which the composer repeatedly argued with his librettists and publisher. Tosca premiered at a time of unrest in Rome, and its first performance was delayed for a day for fear of disturbances. Despite indifferent reviews from the critics, the opera was an immediate success with the public. This classic 1953 EMI recording stars Maria Callas, Giuseppe Di Stefano and Tito Gobbi. Victor de Sabata conducts the La Scala Opera.