Giovanni Boccaccio (UK: bə-KATCH-ee-oh, US: boh-KAH-ch(ee)oh, bə-; Italian: [dʒoˈvanni bokˈkattʃo]; 16 June 1313 – 21 December 1375) was an Italian writer, poet, correspondent of Petrarch, and an important Renaissance humanist. Born in the town of Certaldo, he became so well known as a writer that he was sometimes simply known as "the Certaldese" and one of the most important figures in the European literary panorama of the fourteenth century. Some scholars (including Vittore Branca) define him as the greatest European prose writer of his time, a versatile writer who amalgamated different literary trends and genres, making them converge in original works, thanks to a creative activity exercised under the banner of experimentalism.

His most notable works are The Decameron, a collection of short stories, and On Famous Women. The Decameron became a determining element for the Italian literary tradition, especially after Pietro Bembo elevated the Boccaccian style to a model of Italian prose in the sixteenth century. Bocaccio wrote his imaginative literature mostly in Tuscan vernacular, as well as other works in Latin, and is particularly noted for his realistic dialogue which differed from that of his contemporaries, medieval writers who usually followed formulaic models for character and plot. The influence of Boccaccio's works was not limited to the Italian cultural scene but extended to the rest of Europe, exerting influence on authors such as Geoffrey Chaucer, a key figure in English literature, and the later writers Miguel de Cervantes, Lope de Vega and classical theatre in Spain.

Boccaccio is considered one of the "Three Crowns" of Italian literature along with Dante Alighieri and Petrarch. He is remembered for being one of the precursors of humanism, of which he helped lay the foundations in the city of Florence, in conjunction with the activity of his friend and teacher Petrarch. He was the one who initiated Dante's criticism and philology: Boccaccio devoted himself to copying codices of the Divine Comedy and was a promoter of Dante's work and figure.

In the twentieth century, Boccaccio was the subject of critical-philological studies by Vittore Branca and Giuseppe Billanovich, and his Decameron was transposed to the big screen by the director and writer Pier Paolo Pasolini.