Zaide is an unfinished German-language opera, K. 344, written by Wolfgang Amadeus Mozart in 1780. Emperor Joseph II, in 1778, was in the process of setting up an opera company for the purpose of performing German opera. One condition required of the composer to join this company was that he should write a comic opera. At Salzburg in 1779 Mozart began work on a new opera. It contains spoken dialogue, which also classifies it as a Singspiel. Only the arias and ensembles from the first two acts were composed. Missing are an overture and third act.

The Köchel catalogue is a chronological catalogue of compositions by Wolfgang Amadeus Mozart, originally created by Ludwig Ritter von Köchel, in which the entries are abbreviated K. or KV. Its numbers reflect the ongoing task of compiling the chronology of Mozart's works, and provide a shorthand reference to the compositions.