Wikipedia Reference Information
The Arabic alphabet is the script used for writing languages such as Arabic, Persian, Urdu, and others.
The alphabet was first used to write texts in Arabic -- most importantly, the Qur'an, the holy book of Islam. With the spread of Islam, it came to be used to write many other languages, even outside of the Semitic family to which Arabic belongs. Examples of non-Semitic languages written with the Arabic alphabet include Persian, Urdu, Malay, Azerbaijani (in Iran) and Kurdish in Iraq and Iran. In order to accommodate the needs of these other languages, new letters and other symbols were added to the original alphabet. (See Arabic alphabets of other languages below.)
Just as different handwriting styles and typefaces exist in the Roman alphabet, the Arabic alphabet exists in different styles such as Nasta'liq, Thuluth, Kufic and others (see Arabic calligraphy). These styles can vary widely.
The complete, up-to-date and editable article about Arabic Alphabet can be found at Wikipedia: Arabic Alphabet