Arabic script is a script closely linked to a scripture: The Koran. As the language of the Koran it is considered holy and this has vast implications on Muslim practice.

Before touching questions of faith and religious practice, some formal features have to be considered first. These are crucial also for Arabic script's outstanding importance for Islamic art and architecture:

1. No distinction between cursive writing and block letters but all letters are connected - apart from those, that never must be connected like alif ا, waw و or dal د.
2. Hence, most letters within a word a connected by a line but unlike in Latin script, these lines are most flexible, they can be stretched or compressed according to the writing context. What is most commonly referred to as kashīda in Arabic graphic design and word processing contexts is specific to the Arabic script and allows for alignment by adjusting the lengths of the words themselves, instead of extending spaces between letters and words as in Latin script justification.
3. This way a very close connection between content and form is inherent in Arabic script, giving typography a central role, because
4. Intense stretching of the letter connecting lines allows for making the lines of a poem all appear with the same length. Rhythm and rhymes are graphically stressed.
5. By extending the lines of the inscribed space instead of extending the blank space, words and sentences can be adjusted perfectly to the shape and size of the material carrier.
6. Therefore Arabic script is very suitable for its applicance on objects or in the architectonic space.
7. The line (arab. al-khatt, فن الخط)  is also the decisive element that allows for the much permeable border between calligraphy, floral or ornamentic abstractions, and images created with words by forming a silhouette (i.e.anthropomorphic, zoomorphic, and phytomorphic calligraphy)