Dante Alighieri  (1265–1321) wrote his epic poem, La Divina Commedia (the Divine Comedy), during the last thirteen years of his life (circa 1308-21), while in exile from his native Florence. There are three parts to this massive work: detailing Inferno (Hell), Purgatorio (Purgatory), and Paradiso (Paradise).
In each section Dante the poet recounts the travels of the "Pilgrim" (his alter ego) through Hell, Purgatory, and Heaven, where he meets God face to face. The primary theme is clear. In a letter, Dante once wrote that his poem was, on the literal level, about "The state of souls after death." The poem works on a number of symbolic levels, much like the Bible, one of its primary sources. Similar to the Bible, Dante meant his work and his Pilgrim traveler to serve as models for the reader. He hoped to lead the reader to a greater understanding of his place in the universe and to prepare him for the next life, the life that begins after death.
The Divine Comedy was not titled as such by Dante; his title for the work was simply Commedia or Comedy. Dante’s use of the word “comedy” is medieval by definition. To Dante and his contemporaries, the term “comedy” meant a tale with a happy ending, not a funny story as the word has since come to mean.
The greatness of the Divine Comedy lies in its construction as a Summa, or a summation of knowledge and experience. Dante was able to weave together pagan myth, literature, philosophy; Christian theology and doctrine, physics, astrology, cartography, mathematics, literary theory, history, and politics into a complex poem that a wide audience, not just the highly educated, could read. For Dante boldly chose to write his poem of salvation in his own Italian dialect, not in Latin, which was the language of Church, State, and epic poetry during his time. Its impact was so great that Dante's Tuscan dialect became what we recognize as modern Italian.
As one of the greatest works, not just of the late Middle Ages but of world literature in its entirety, the influence of the Divine Comedy has been incalculable. The poem was immediately successful— Dante's own sons, Pietro and Jacopo, wrote the first commentaries on it—and it continues to be read and taught today. Many of western literature's major figures were indebted to Dante's masterwork. Dante’s autobiographical Inferno contains one of the most detailed and influential literary descriptions of Hell ever written.
In this chapter, Dante wanders through the nine circles of Hell. The circles are concentric, representing a gradual increase in wickedness, and culminating at the center of the earth, where Satan is held in bondage. Each circle's sinners are punished in a fashion fitting their crimes: each sinner is afflicted for all of eternity by John sin he committed. People who sinned but prayed for forgiveness before their deaths are found in Purgatory - where they labor to be free of their sins - not in Hell. Those in Hell are people who tried to justify their sins and are unrepentant.
The canto opens with Dante wondering how to describe the sinners in the ninth chasm (the circle reserved for only the vilest of sinners). This is the place of the Sowers of Discord and Scandal, and the Creators of Schism within the papacy (the Avignon Papacy was the period from 1309 to 1377 during which seven popes, all French, resided in Avignon, France). He warns that the punishment in this part of Hell is bloody and grotesque. Indeed, the sinners in the ninth chasm are damned to walk around the chasm until they arrive at a devil who slashes them with a long sword, according to the nature of their sin.
It is in this Ninth Circle of Hell that Dante meets tortured Shades (the spirits of dead men) who ask favors of him, many wishing him to bring messages and advice to their friends and kin in the world of the living.
During the final battle in the novel Ghosts of Onyx, Senior Chief Petty Officer Franklin Mendez mentions that the 13 ascending rings near the core of the planet Onyx reminds him of Dante's Inferno. Dr. Catherine Halsey then corrects him stating that "Dante's Hell was a series of descending rings" She then continues saying that "These are more representative of-" before being cut off by one of the 13 rings settling into the floor of the large Forerunner room of which they were in. Although her thought was never finished, it is safe to guess that she would have likened the 13 forerunner rings to Dante's Purgatory, consisting of 7 ascending terraces leading up to Terrestrial Paradise.
There are also a number of parallels between Inferno and Halo 3: ODST: the protagonist is guided through "hell on earth" by Vergil, descending nine levels underground in his journey. Each of the "Circles" of Audio Logs also seems to represent the sin embodied by the respective level of hell described in Inferno.