Arabic papyri provide a window into the development of Arabic writing and insight into early Islamic history and culture.
The style of the writing found in most Arabic papyri is sometimes classified as Naski, a broad general term refering to a family of small rounded scripts with open loops. However, actual classification can be difficult, because the writing is often not carefully executed and does not adhere to a particular style. Carefully written scripts conforming to a standard style were typically limited to Qur'ans, high literary texts, and govermental or official documents and rarely used for private personal documents which make up a large percentage of the surviving Arabic papyri. Also, specific rules of style would not be established (codified) until the tenth century CE when the use of papyrus as a writing surface was almost at an end.
Generally, Arabic papyri from the first two centuries of the Islamic era (mid 7th to mid 9th centuries CE) are more carefully executed than later ones and often exhibit a writing style resembling the contemporary monumental script found on inscriptions (on stone, etc.), on coins, and in Qur'an manuscripts. After the second century AH (mid 9th century CE) the script becomes increasingly cursive and rounded.
The way individual letters were written also changed over time. One example, the letter 'alif, bends to the right at the bottom or (less often) is straight in papyrus documents dating from before the third century AH. After the second century AH, it bends to the left.