Haruffan Larabci, kamar yadda muka sansu a yau, an hada su ne da layuka da digo. Ana kiran digon nan i'jam. Tsohon rubutun Larabci bai da su, sai dai ya kunshi layuka kawai.

The Arabic letters, as we know them today, are made up of lines and points. The latter are called i'jam. The ancient Arabic script did not have them, but consisted of strokes only.

Ƙarin ɗigon harshe a kan rubutun ƙwanƙwasa ya taimaka wajen bambance haruffa daban-daban waɗanda cikin sauƙi za a iya rikitar da su.

The addition of diacritical points to the plain writing of strokes helped to distinguish the various letters which could be easily mixed up.

Misali: XXX XXX Ba tare da digoge-digoge ba, wannan kalma ba za a iya gane ta cikin sauƙi ba. Tare da i'jam, harrufan wannan kalma za a iya bambance su cikin sauƙi.

Example: XXX XXX Without dots this word cannot be easily recognized. With i'jam, the letters of this word can easily be distinguished.

Duk da cewa an riga an san alamomin i'jam (digo-digon harafi) tun zamanin jahiliyya, ba a cika amfani da su ba. Kwafen Alƙur'ani mafi tsufa (da kuma rubutun Larabci gaba ɗaya) ba su da waɗannan alamomi. An ce an saka su cikin rubutun Alƙur'ani a zamanin halifa na biyar na Daular Umayyawa, 'Abd al-Malik bin Marwan (66-86H/685-705), da lokacin gwamnatin Al-Hajjaj a Iraƙi, lokacin da ƙarin Musulmi suka fara karatu da nazarin Alƙur'ani, wasu daga cikinsu ba su san Alƙur'ani sosai ba, wasu kuma ba asalin Larabawa ba ne. An ce shahararren tabi'i Al-Du'ali shi ne farkon wanda ya saka waɗannan digo-digo cikin rubutun Alƙur'ani.

Although the i'jam (diacritical points) were already known in pre-Islamic times, they were rarely used. The very early copies of the Qur'anic manuscripts (and Arabic writing in general) did not have these signs. They were apparently introduced into the Qur'anic script during the time of the fifth Umayyad Caliph, 'Abd al-Malik bin Marwan (66-86H/685- 705) and the governorship of Al-Hajjaj in Iraq, when more and more Muslims began to read and study the Qur'an, some of whom did not know much of the Qur'an, and others were of non-Arab origin. It is said of the well-known tabi'l Al-Du'all that he was the first to introduce these points into the Qur'anic text.