The cabaletta formed as part of an evolution from early 19th century arias containing two contrasting sections at different tempi within a single structure into more elaborate arias with musically distinct movements. The term itself was first defined in 1826. It has a repetitive structure consisting of two stanzas followed by embellished variations. The cabaletta typically ends with a coda, often a very virtuosic one.
In later parlance, cabaletta came to refer to the fast final part of any operatic vocal ensemble, usually a duet, rather than just a solo aria: the duet between Gilda and Rigoletto in Rigoletto ends with a relatively slow cabaletta.
The Cabaletta is often used to convey strong emotions: overwhelming happiness (Linda's famous cabaletta "O luce di quest anima" from Donizetti's Linda di Chamounix), great sorrow (Lucia's "Spargi d'amaro pianto" from Lucia di Lammermoor), timeless love (Lindoro's short cabaletta from Rossini's L'italiana in Algeri). Cabaletta is one of the most important elements in opera, particularly in belcanto opera: Rossini, for example, wrote at least one or even more cabalettas for all major characters in his operas (for example, L'italiana in Algeri contains two cabalettas for Lindoro, three cabalettas for Isabella, one cabaletta for Mustafa, and one for Taddeo; and if we add the final parts of the ensembles: we get almost sixteen cabalettas).
Giuseppe Verdi continued to adapt the aria-cabaletta formula to great emotional and dramatic effect, as in Violetta's pensive "È strano! è strano..." (La traviata, I, v) which leads by degrees to her resolve, "Sempre libera", with its rapid and defiant pyrotechnics.