The Arabic alphabet (, or , ), or Arabic abjad, is the Arabic script as it is codified for writing Arabic. It is written from right to left in a cursive style and includes 28 letters. Most letters have contextual letterforms. The Arabic alphabet is considered an abjad, meaning it only uses consonants, but it is now considered an "impure abjad". As with other impure abjads, such as the Hebrew alphabet, scribes later devised means of indicating vowel sounds by separate vowel diacritics. Consonants The basic Arabic alphabet contains 28 letters. Adaptations of the Arabic script for other languages added and removed some letters, as for example Persian, Ottoman Turkish, Kurdish, Urdu, Sindhi, Azerbaijani (in Iran), Malay, Pashto, Punjabi, Uyghur, Arwi and Arabi Malayalam, all of which have additional letters as shown below. There are no distinct upper and lower case letter forms. Many letters look similar but are distinguished from one another by dots () above or below their central part (). These dots are an integral part of a letter, since they distinguish between letters that represent different sounds. For example, the Arabic letters ب (b), ت (t) and ث (th) have the same basic shape, but have one dot below, two dots above and three dots above, respectively. The letter ن (n) also has the same form in initial and medial forms, with one dot above, though it is somewhat different in isolated and final form. Both printed and written Arabic are cursive, with most of the letters within a word directly connected to the adjacent letters. Alphabetical order There are two main collating sequences for the Arabic alphabet: abjad and hija. The original order (), used for lettering, derives from the order of the Phoenician alphabet, and is therefore similar to the order of other Phoenician-derived alphabets, such as the Hebrew alphabet. In this order, letters are also used as numbers, Abjad numerals, and possess the same alphanumeric code/cipher as Hebrew gematria and Greek isopsephy. The () or () order, used where lists of names and words are sorted, as in phonebooks, classroom lists, and dictionaries, groups letters by similarity of shape. Abjadī The order is not a simple historical continuation of the earlier north Semitic alphabetic order, since it has a position corresponding to the Aramaic letter samekh/semkat , yet no letter of the Arabic alphabet historically derives from that letter. Loss of was compensated