The objects are single man-made artefacts or documents, excluding buildings, ranging in date from about 5,000 BC (Mesolithic) to the early 21st century.
[1] Details of the hundred objects, written by Irish Times journalist Fintan O'Toole, were initially serialized in The Irish Times between February 2011 and January 2013.
In February 2013 a book about the hundred objects written by O'Toole, entitled A History of Ireland in 100 Objects, was published, and it quickly became a best-seller with 35,000 free downloads.
[2] In January 2017 An Post announced that a selection of the 100 objects would form the subjects for the 9th definitive postage stamp series for Ireland, to be issued over a period of five or six years from 2017.
[1] Objects for which there is a specific Wikipedia article are given in bold type.