A sonnet is a poetic form that originated in the poetry composed at the Court of the Holy Roman Emperor Frederick II in the Sicilian city of Palermo. The 13th-century poet and notary Giacomo da Lentini is credited with the sonnet's invention, and the Sicilian School of poets who surrounded him then spread the form to the mainland. The earliest sonnets, however, no longer survive in the original Sicilian language, but only after being translated into Tuscan dialect.

The term "sonnet" is derived from the Italian word sonetto (lit. "little song", derived from the Latin word sonus, meaning a sound). By the 13th century it signified a poem of fourteen lines that followed a strict rhyme scheme and structure.

According to Christopher Blum, during the Renaissance, the sonnet became the "choice mode of expressing romantic love". During that period, too, the form was taken up in many other European language areas and eventually any subject was considered acceptable for writers of sonnets. Impatience with the set form resulted in many variations over the centuries, including abandonment of the quatorzain limit and even of rhyme altogether in modern times.