Short answers, pulled from the story.
Heimskringla is most commonly attributed to the Icelandic knight, poet, and historian Snorri Sturluson, who lived from 1178 or 1179 until 1241. No surviving manuscript names an author, and the attribution to Snorri first appears in 16th-century Danish translations by Peder Claussøn Friis and Laurents Hanssøn, who are believed to have used a now-lost manuscript that identified him.
Heimskringla was composed around 1230 in Iceland, written in Old Norse. The title itself was not used in print until 1697, when Johan Peringskiöld published a Swedish and Latin edition in Stockholm.
Heimskringla derives from the opening words of the first saga in the collection, Ynglinga saga, which begins with the phrase kringla heimsins, meaning "the orb of the Earth" or "the circle of the world" in Old Norse.
Heimskringla spans from the mythological prehistory of the Yngling dynasty, whose lineage is traced to the god Freyr and the legendary Asgard, through historical Norwegian rulers beginning with Harald Fairhair in the 9th century, up to the death of the pretender Eystein Meyla in 1177.
Historians today treat Heimskringla with caution. Saga criticism, pioneered by the Swedish historians Lauritz and Curt Weibull in the early 20th century, highlighted that the work was written several centuries after most events it describes. The later portions are considered more credible than the early mythological sagas, since shorter gaps in time allowed oral traditions to remain more accurate.
The oldest surviving parchment is a single vellum leaf dated around 1260, catalogued as Lbs fragm 82 and held at the National and University Library of Iceland. It contains a portion of the Saga of St. Olaf; the rest of that manuscript was destroyed by fire in 1728.