Ptolemy V assumed the crown at the age of five after a rather turbulent time in Egyptian history. The young ruler was faced with the daunting task of reclaiming lands lost to various invaders and reunifying his country's populace. As an attempt to reestablish legitimacy for the ruler and create a royal cult, Ptolemy's priests issued a series of decrees. The decrees were inscribed on stones and erected throughout Egypt. The Rosetta stone is a copy of the decree issued in the city of Memphis.

The Greeks had the habit of making bilinguals in territories they occupied, and in this case we have Egyptian, and Greek. Thus the Egyptian hieroglyphs, and the Egyptian Demotic (citizen text, as in democratic), was written against the Greek language, as the new occupiers of pharaonic rule, following Alexander the Great's conquest.

The Rosetta Stone is stone three in a series of three, a stone each for Ptolemy III, Ptolemy IV, and the Rosetta Stone, for Ptolemy V. Leap Year is implemented in Stone 1, the Stone of Canopus, for Ptolemy III.

There are approximately two copies, of the Stone of Canopus, two of stone 2 (one imperfect), The Memphis Stele, and two and a half copies of the Rosetta Stone, including the Nubayrah Stele, and a pyramid Wall inscription, with editings because of overwriting by scene replacements by subsequent scribers.

Condensed listing, the three decrees, the three-stone series

• 239 BC Decree of Canopus (Ptolemy III), (247–221 BC)

  stone 1: Stele of Canopus, (no. 1), found 1866, 37 lines hieroglyphs, 74 lines Demotic (right side), 76 lines Greek 'capitals', fine limestone.
  stone 2: Stele of Canopus, no. 2, found 1881, 26 lines hieroglyphs, 20 lines Demotic, 64 lines Greek 'capitals', white limestone.
  3rd partial of hieroglyphic lines (location: Louvre).

• 216 BC Decree of Memphis (Ptolemy IV), (221–203 BC)

  stone 1: Stele No. 1, found 1902, hieroglyphs, demotic, and Greek, dark granite.
  stone 2: Pithom Stele, No. II, found 1923, hieroglyphs (front), 42 lines Demotic (back), virtually complete providing almost total translation, and Greek (side), sandstone.

• 196 BC Decree of Memphis (Ptolemy V), (203–198 BC)

  stone 1: Rosetta Stone, "Stele of Rosetta", found 1799, (remaining) hieroglyphs, 1987 lines, 2 lines Demotic, 1985 lines Greek 'capitals', dark granite.
  stone 2: Stele of Nubayrah, found early 1650s, hieroglyphs, lines 1–300 used to complete missing Rosetta Stone lines, demotic, Greek capitals.
  site 3: the Temple of Philae, inscribed hieroglyphs, for Decree of Memphis (Ptolemy IV), on fllors, also overwritten, by scenes, and figures of humans/gods.

History of the stone

Some scientists accompanied Napoleon's French campaign in Egypt (1798–1801). After Napoleon Bonaparte founded the Institut de l'Égypte in Cairo in 1798 some 50 became members of it. When Bouchard discovered the stone, he immediately understood the importance of the stone and showed it to General Abdallah Jacques de Menou who decided that it should be brought to the institute, where it arrived in August, 1799.

The French scientist Étienne Geoffroy Saint-Hilaire, writing to the English diplomat William Richard Hamilton, threatened to burn all their discoveries, ominously referring to the burned Library of Alexandria. The British gave in and insisted only on the delivery of the monuments. The French tried to hide the Rosetta Stone in a boat despite the clauses of the capitulation, but failed. The French were allowed to take the imprints they had made previously, when embarking in Alexandria.

When it was brought back to Britain, it was presented to the British Museum, where it has been kept since 1802.

In 1814 Thomas Young finished translating the enchorial (demotic) text, and went on to work on the hieroglyphic alphabet.

During the years of 1822–1824, Jean-François Champollion greatly expanded on his work, and he is known as the translator of the Rosetta Stone. Champollion could read both Greek and coptic. He was able to break the hieroglyphic code by comparing it with the other two languages, which were translations of the same text. This discovery of the Rosetta Stone made it possible for scholars to translate Egyptian texts and to understand the historical background of Israel's history.

In 1858, the Philomathean Society of the University of Pennsylvania published of the first complete English translation of the Rosetta Stone. The work was performed solely by three undergraduate members, Charles R Hale, S Huntington Jones, and Henry Morton. The translation quickly sold out two editions, and was internationally hailed as a monumental work of scholarship. In 1988, the British Museum bestowed the honor of including the Philomathean Rosetta Stone Report in its select bibliography of the most important works ever published on the Rosetta Stone. The Philomathean Society maintains a full-scale cast of the stone in its meeting room at the University of Pennsylvania.

White painted inscriptions, contemporary with its acquisition, record on the left side 'Captured in Egypt by the British Army in 1801' and on the right 'Presented by King George III'. The stone was cleaned by the British Museum in 1998, and this evidence of its history was not removed. A small area of the surface at the bottom left-hand corner was also left uncleaned for comparative purposes.

In July 2003, the Egyptians demanded the return of the Rosetta Stone. Dr. Zahi Hawass, secretary general of the Supreme Council of Antiquities in Cairo, told the press: "If the British want to be remembered, if they want to restore their reputation, they should volunteer to return the stone because it is the icon of our Egyptian identity."

Rosetta Stone is also used as a metaphor to refer to anything that is a critical key to a process of decryption, translation, or a difficult problem, e.g., "the Rosetta stone of immunology", "thalamo-cortical rhythms, the Rosetta stone of a subset of neurological disorders", "Arabidopsis, the Rosetta stone of flowering time (fossils)".