Short answers, pulled from the story.
The Rosetta Stone is a stele of granodiorite that bears three versions of a decree issued in 196 BC during the Ptolemaic dynasty of Egypt. The stone measures approximately 1.14 meters in height, 0.73 meters wide, and weighs roughly 762 kilograms.
Lieutenant Pierre-François Bouchard spotted the slab with inscriptions during demolition work at Fort Julien near Rashid in mid-July 1799. French soldiers under Colonel d'Hautpoul were strengthening defenses there when he made the discovery alongside his commander General Jacques-François Menou.
Jean-François Champollion announced the transliteration of Egyptian scripts in Paris on the 27th of September 1822. He completed this work on the 14th of September 1822 after constructing an alphabet of phonetic hieroglyphic characters based on foreign names found in cartouches.
The Rosetta Stone has been exhibited almost continuously in the British Museum since June 1802. It left the museum only once for one month in October 1972 to be displayed alongside Champollion's Lettre at the Louvre in Paris.
Zahi Hawass described the stele as the icon of Egyptian identity and served as Secretary-General of Egypt's Supreme Council of Antiquities when he made calls for its return in July 2003. He reiterated his demands for permanent return in August 2022 while listing other key items belonging to Egypt's cultural heritage.