Sumerian was one of the two main languages spoken in ancient Iraq, the other being Akkadian. During the third millennium BCE, the two languages entered what linguists call a Sprachbund, meaning that they were spoken side by side in the same region and substantially influenced one another. However, in linguistic terms, Sumerian and Akkadian could hardly be more different. Akkadian is a Semitic language, related to Arabic and Hebrew, while Sumerian is an isolate, meaning that it is unrelated to any other known language.
Sometime around the year 2000 BCE, Sumerian ceased to be spoken as a native language, but that did not mean that it stopped being used, only that it had to be learned in schools. Sumerian continued to hold great cultural prestige, serving as a language of religious rituals and educated scholarship until the last century BCE.
A distinguishing feature of Sumerian is what linguists call the agglutinative nature of the language, meaning that it chains together short words into longer constructions, which then become grammatical units in their own right. For example, on the Disk, Enheduana calls herself “child of Sargon, king of the world” (dumu Šarrūkin lugal kiš), and that forms a composite grammatical unit in Sumerian, which can be parsed as: “child Sargon (king everything-of)-of.”
A statue of king Gudea, now in the Metropolitan Museum of Art. Wikimedia Commons.
This feature shaped the way the cuneiform script developed. Cuneiform is the world’s oldest writing system, as it was probably created by Sumerian-speaking peoples in the mid-fourth millennium BCE. It went on to be used for three and a half thousand years, dying out in the first century CE.
Because of the tendency of Sumerian to create longer chains made up of small elements, each sign in the new script generally came to represent one such element: dumu, “child,” lugal, “king,” kiš, “everything” are one sign each. However, cuneiform is not strictly ideographic, meaning that one sign does not always correspond to one word or idea. Instead, cuneiform is a mixed system, where signs can represent both whole words and single syllables.
Another key feature of the cuneiform script is its polysemy, meaning that the vast majority of cuneiform signs have more than one meaning. Some signs, especially in later periods, could have dozens of different meanings; conversely, many sounds can be represented by different signs. Subscript numbers are used to differentiate between different signs that denote the same sound: for example, du3 means “to create” and du11 “to speak” (an ambiguity employed in the Exalatation, l. 138). Superscript letters mean that the sign is a determinative, that is, that it denotes the nature of the word next to it: the d in dinana is the sign diĝir, which on its own means “deity” but here denotes that the name Inana is the name of a deity.
Finally, the transliteration of Sumerian uses a set of special characters: š marks a sound like English sh, and ĝ a sound like ng (though in Sumerian it can also appear at the beginning of a word, as in ĝipar).
Cuneiform was eventually adapted to represent other languages as well, especially Akkadian, but also Hittite, Elamite, Hurrian, and a range of others. Because learning cuneiform always involved learning the literature and scholarship that was written in the script, one may speak of a cuneiform culture that persisted for more than three thousand years and spread across the ancient Near East.
Further reading
Enheduana 
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