Gradual steps were taken to improve the orthography of the Quran, in the first century with dots to distinguish similarly-shaped consonants (predecessors to i‘jām), followed by marks (to indicate different vowels, like ḥarakāt) and nunation in different-coloured ink from the text (Abu'l Aswad ad-Du'alî (d. 69 AH/688 CE). (Not related to the colours used in the graphic to the right.) Later the different colours were replaced with marks used in written Arabic today.
