Most entries consist of only one or two sentences, and some years contain only one or two entries.
The Viking raid on Iona Abbey in 806, in which the entire population of the abbey was massacred, is recorded with typical brevity: "The community of Iona was killed by the gentiles, that is sixty-eight (referring to the number of dead)." There is no direct evidence for the identity of the Chronicle's successive authors, but scholars are confident that it was produced by annalists working in churches and monasteries and was intended for an ecclesiastical audience.
Other entries include observations of astronomical events, such as a solar eclipse that took place on June 29, 512.
"The Chronicle of Ireland" represents the scholarly consensus solution to this Gaelic synoptic problem.
Events are listed in separate entries under the heading of a single year.
Several surviving annals share events in the same sequence and wording, until 911 when they continue separate narratives.
They include the Annals of Inisfallen, the Annals of Ulster, the Chronicon Scotorum, the Annals of Clonmacnoise, the Annals of Tigernach, the Annals of Roscrea, the Annals of Boyle, and the Fragmentary Annals of Ireland.
The version of the Chronicle that annalists and chroniclers were working from was written in different places at different times; the earliest evidence for one of its authors places it in Iona sometime after 563, continuing until about 642.
Some scholars believe that work may have moved to Armagh by the beginning of the 9th century, but debate continues on this point.
After 911, the Chronicle's descendants break into two main branches: one in Armagh, which was integrated into the Annals of Ulster; and a "Clonmacnoise group" including the Annals of Clonmacnoise (an English translation), the Annals of Tigernach (fragmentary), the Chronicum Scotorum (an abbreviation of Tigernach), and the Annals of the Four Masters.
The cause of death was significant to the annalists as an indicator of the death's "spiritual quality"; they felt it indicated whether the deceased would go to Heaven or Hell.
After 800, records of Viking raids (as in the example above) also make up a large number of entries.
Most surviving witnesses to the lost Chronicle's original content are descended from the Clonmacnoise chronicle.
A large number of the Chronicle's entries are obituaries.