Short answers, pulled from the story.
Dante Alighieri began the Divine Comedy around 1308 and completed it around 1321, shortly before his death. The poem is set during the spring of 1300, running from the night before Good Friday to the Wednesday after Easter.
The Divine Comedy contains 14,233 lines divided into 100 cantos. Each of the three cantiche, Inferno, Purgatorio, and Paradiso, contains 33 cantos, with one additional introductory canto bringing the total to 100.
Dante is guided through Hell and most of Purgatory by the Roman poet Virgil, who represents human reason. Beatrice, representing divine revelation, theology, grace, and faith, guides him from the end of Purgatorio through Heaven. Saint Bernard of Clairvaux, representing contemplative mysticism, leads Dante through the final cantos of Paradiso.
Dante chose to write in the Tuscan vernacular, the everyday language of ordinary Florentines, rather than the Latin expected for serious medieval subjects. He was one of the first medieval writers to treat a profound subject, the Redemption of humanity, in a 'low' vernacular language. The choice helped establish Tuscan as the foundation of standardized Italian.
Contrapasso is the principle by which each punishment in Hell is a symbolic instance of poetic justice matching the sinner's offense. Fortune-tellers, for example, must walk with their heads on backwards because in life they tried to see what lay ahead. The principle governs the moral logic of all nine circles of Hell.
The first printed edition was published on the 11th of April 1472, in Foligno, Italy, by Johann Numeister and Evangelista Angelini da Trevi. Of the 300 copies printed, fourteen still survive, and the original printing press is on display at the Oratorio della Nunziatella in Foligno.