Who invented the sonnet which was the most important poetic genre in the Renaissance Period?

Giacomo da Lentini, an Italian poet of the 13th century, is credited with the invention of the sonnet. He was a senior poet of the Sicilian School and was a notary at the court of the Holy Roman emperor Frederick II. During his life, Giacomo exchanged sonnets with other Italian poets, Abate di Tivoli, Jacopo Mostacci, and Pier delle Vigne (probably 1241-1242).

Now it is Giacomo who is considered the real initiator of a poetical tradition (poets writing sonnets). He is responsible for the systematic transposition of Old Provencal lyric models (the earliest form of the Occitano-Romance languages) into an Italian vernacular.

His literary and chronological primacy is corroborated by the quantity of his extant poems (some 39 pieces). They are now included in a very important and substantial collection of Old Italian poetry.