Arabic script has a genetic relationship with the Latin alphabet, since both are historically traceable back to a script current on the Levant coast around 1000 B.C. and used for the notation of the language which we call Old Phoenician. The Old Phoenician script had a repertory of 22 symbols, all written individually. The values of the symbols were exclusively consonantal, showing no means of noting a vowel at all.

In the 8th century B.C., the Old Phoenician script was employed for the rendering of Old Aramaic, but with one seminal development, namely the use of a few of the symbols as vowel notation. These "vowel" symbols preserved their consonantal value, though, and were henceforth ambiguous. A century or so later, the Greeks borrowed the script, but abandoned the consonantal value of the letters. Thus, the Greek alphabet is classifiable into mutually exclusive groups of consonants and vowels. The Greek alphabet is the ancestor of modern European script.

About the same time also, a form of script was introduced into South Arabia which had affinities with the Old Phoenician script, but which expanded the range of the alphabet into 29 symbols with distinctive shapes, in order to cope with the phonemic consonantal repertory of the South Arabian language. Script forms closely analogous to this became widely prevalent throughout the south and center of the Arabian peninsula, where they remained in normal use down to the 5th century A.D., but thereafter fell into disuse.

Aramaic script evolved through many centuries without taking the step which the Greeks had, so that its facilities for vowel notation remained restricted. By the early centuries A.D., it developed into Syriac script, used for the dialect of near eastern Christians, and into varieties used by the pagan kingdoms of Palmyra and Nabatene. Syriac, Palmyrene and Nabataean are all characterized by the fact that the custom had developed of linking many of the letters together with the boundaries of a single word by "ligatures", as in modern European handwriting forms. This has two results. First, certain letters, came to have different shapes when occurring at the end of a word from those appearing elsewhere. Second, certain letters tended to lose their distinctive linear shapes and become ambiguous. In Syriac, for example, the letter d and r became linearly indistinguishable, and where differentiated by the device of placing a dot under or over the letter. In Palmyrene, and Nabataean, the ambiguity brought by the use of ligatures was even more marked, but no attempts was made to obviate the confusion by the use of dots. As a result, these scripts are extremely difficult to interpret.

The earliest manifestation of a script form which can be identified as Arabic is on a tombstone at Nemara in the Syrian desert, dated A.D. 328 and one or two similar inscriptions from the 5th - 6th century. The script of the Nemara inscription is essentially a Nabataean one. It shows no notation at all for an open-quality vowel nor for any short vowel. Long u and i are marked by ambiguous letters serving also for the consonantal values w and y. The length of consonants in Nabataean script is not marked at all, and it is still limited to the repertory of the Aramaic script, which is inadequate for the consonant phonemes of Arabic.

Today, it is widely believed that Arabic script is a descendent of the Nabataean script. Apart from the Nemara and a few other inscriptions, the earliest surviving document of written Arabic is the Quran, Islam's sacred book revealed to the Prophet Mohammed in the early 7th century A.D. Early Arabic script employed to record the Quran shares several characteristics with the Nemara script such as the use of symbols which hold resemblance in their shapes to denote distinct letters, as in the case of the letters b, t, and th. With the development of the Arabic writing system, more subtleties and refinements were added. During the first year in the Islamic calendar, dots above or below letters were systematically used to differentiate between letters which were identical without the dots. Thus the letters b, t, and th were marked with one dot below (b), two dots above(t), and three dots above (th). And it was not until the early 8th century A.D. that the use of diacritical marks was introduced to secure the correct reading of the Quran. The diacritical system (probably borrowed from the Syriac script) employed short vowels, marked by symbols placed above or below the consonant which they follow in speech. Other symbols placed above the letter marked the absence of a following vowel (sukun), and others, the endings in the inflection of nouns and the moods of verbs. But these marks never came into general use, and to the present day, the system is used mainly in text of the Quran and for teaching purposes.