Dante’s letters (named Epistulae in Latin) are 13, all written in Latin language. They are about various topics and they all are a very important biographical source on Dante’s life. Originally there were more, but some of them have been lost.
The first is addressed to cardinal Niccolò from Prato.
The second is addressed to the counts of Romena.
The third is to Dante’s friend named Cino, who’s in exile similarly to Dante.
The fourth is to marquis Moroello Malaspina.
The fifth, sixth, seventh, eight, ninth and tenth letters are all about Emperor Henry VII and his arriving in Italy.
The eleventh letter is addressed to Italian cardinals and is a suggestion about the election of the new Pope.
The twelfth is addressed to a Florentine friend of Dante’s.
The thirteenth is to Cangrande della Scala. In this letter, Dante dedicates the Paradiso to the duke and explains some ways of reading his Divina Commedia.
All the letters are written in a very affected and refined style, according to the rules of the times.