stylistic:tone, information:extraction, stylistic:style_transfer, linguistic:voice_change, structural:expansion
Early Dynastic cuneiform (circa 2500 BC)

Early cuneiform inscriptions were made by using a pointed stylus, sometimes called "linear cuneiform". Many of the early dynastic inscriptions, particularly those made on stone, continued to use the linear style as late as circa 2000 BC.

In the mid-3rd millennium BC, a new wedge-tipped stylus was introduced which was pushed into the clay, producing wedge-shaped cuneiform. This development made writing quicker and easier, especially when writing on soft clay. By adjusting the relative position of the stylus to the tablet, the writer could use a single tool to make a variety of impressions. For numbers, a round-tipped stylus was initially used, until the wedge-tipped stylus was generalized. The direction of writing was from top-to-bottom and right-to-left. Cuneiform clay tablets could be fired in kilns to bake them hard, and so provide a permanent record, or they could be left moist and recycled if permanence was not needed. Most surviving cuneiform tablets were of the latter kind, accidentally preserved when fires destroyed the tablets' storage place and effectively baked them, unintentionally ensuring their longevity.

The script was widely used on commemorative stelae and carved reliefs to record the achievements of the ruler in whose honor the monument had been erected. The spoken language included many homophones and near-homophones, and in the beginning, similar-sounding words such as "life" and "arrow" were written with the same symbol (𒋾). As a result, many signs gradually changed from being logograms to also functioning as syllabograms, so that for example, the sign for the word "arrow" would become the sign for the sound "ti".

Syllabograms were used in Sumerian writing especially to express grammatical elements, and their use was further developed and modified in the writing of the Akkadian language to express its sounds. Often, words that had a similar meaning but very different sounds were written with the same symbol. For instance the Sumerian words 'tooth', 'mouth' and 'voice' were all written with the original pictogram for mouth (𒅗).

Words that sounded alike would have different signs; for instance, the syllable had fourteen different symbols.

The inventory of signs was expanded by the combination of existing signs into compound signs. They could either derive their meaning from a combination of the meanings of both original signs (e.g. 𒅗 ka 'mouth' and 𒀀 a 'water' were combined to form the sign for 𒅘 nag̃ 'drink', formally KA×A; cf. Chinese compound ideographs), or one sign could suggest the meaning and the other the pronunciation (e.g. 𒅗 ka 'mouth' was combined with the sign 𒉣 nun 'prince' to express the word 𒅻 nundum, meaning 'lip', formally KA×NUN; cf. Chinese phono-semantic compounds).

Another way of expressing words that had no sign of their own was by so-called 'Diri compounds' – sign sequences that have, in combination, a reading different from the sum of the individual constituent signs (for example, the compound IGI.A (𒅆𒀀) – "eye" + "water" – has the reading imhur, meaning "foam").

Several symbols had too many meanings to permit clarity. Therefore, symbols were put together to indicate both the sound and the meaning of a symbol. For instance, the word 'raven' (UGA) had the same logogram (𒉀) as the word 'soap' (NAGA), the name of a city (EREŠ), and the patron goddess of Eresh (NISABA). To disambiguate and identify the word more precisely, two phonetic complements were added – Ú (𒌑) for the syllable in front of the symbol and GA (𒂵) for the syllable behind. Finally, the symbol for 'bird', MUŠEN (𒄷) was added to ensure proper interpretation. As a result, the whole word could be spelt 𒌑𒉀𒂵𒄷, i.e. Ú.NAGA.GA (among the many variant spellings that the word could have).

For unknown reasons, cuneiform pictographs, until then written vertically, were rotated 90° counterclockwise, in effect putting them on their side. This change first occurred slightly before the Akkadian period, at the time of the Uruk ruler Lugalzagesi (r. c. 2294–2270 BC). The vertical style remained for monumental purposes on stone stelas until the middle of the 2nd millennium.

Written Sumerian was used as a scribal language until the first century AD. The spoken language died out between about 2100 and 1700 BC.