A leitmotif is a recurring musical theme associated with a particular character, idea, or situation in a composition, particularly in operas and film scores. This technique helps to unify a work and evoke specific emotions or memories related to the associated elements. It was notably used by composers like Richard Wagner in his operas and has influenced many modern film composers. By reintroducing these motifs throughout a piece, the composer can deepen the audience's connection to the narrative and characters.