Aria is a self-contained vocal solo in opera or oratorio that lets a single character express an emotion at length.
An aria is the operatic moment in which the narrative pauses and a character steps forward to inhabit a single feeling fully. Born in early Italian opera around 1600 and codified in the Baroque era, the aria reached its first formal peak in the da capo aria — A-B-A structure with elaborate ornamentation on the return — favoured by Handel and Vivaldi. Mozart simplified and humanised the form: the Countess's 'Dove sono' in 'Le nozze di Figaro' (1786) compresses years of marital sorrow into seven minutes. The 19th century brought the long-breathed Italian aria of Bellini, Donizetti, and Verdi, and the through-composed scenes of Wagner that dissolved the aria into continuous music. By the 20th century, Puccini's 'Nessun dorma' from 'Turandot' (1926) showed the form still capable of stopping the world. The aria is opera's beating heart: every other element — recitative, ensemble, chorus — exists to deliver the audience to it.