The Arabic script has numerous diacritics, which include: consonant pointing known as iʻjām (إِعْجَام), and supplementary diacritics known as tashkīl (تَشْكِيل). The latter include the vowel marks termed ḥarakāt (حَرَكَات; singular: حَرَكَة, ḥarakah).
The Arabic script is a modified abjad, where short consonants and long vowels are represented by letters but short vowels and consonant length are not generally indicated in writing. Tashkīl is optional to represent missing vowels and consonant length. Modern Arabic is always written with the i‘jām—consonant pointing, but only religious texts, children's books and works for learners are written with the full tashkīl—vowel guides and consonant length. It is however not uncommon for authors to add diacritics to a word or letter when the grammatical case or the meaning is deemed otherwise ambiguous. In addition, classical works and historic documents rendered to the general public are often rendered with the full tashkīl, to compensate for the gap in understanding resulting from stylistic changes over the centuries.
The literal meaning of تَشْكِيل tashkīl is 'forming'. As the normal Arabic text does not provide enough information about the correct pronunciation, the main purpose of tashkīl (and ḥarakāt) is to provide a phonetic guide or a phonetic aid; i.e. show the correct pronunciation. It serves the same purpose as furigana (also called "ruby") in Japanese or pinyin or zhuyin in Mandarin Chinese for children who are learning to read or foreign learners.
The bulk of Arabic script is written without ḥarakāt (or short vowels). However, they are commonly used in texts that demand strict adherence to exact pronunciation. This is true, primarily, of the Qur'an ⟨ٱلْقُرْآن⟩ (al-Qurʾān) and poetry. It is also quite common to add ḥarakāt to hadiths ⟨ٱلْحَدِيث⟩ (al-ḥadīth; plural: al-ḥādīth) and the Bible. Another use is in children's literature. Moreover, ḥarakāt are used in ordinary texts in individual words when an ambiguity of pronunciation cannot easily be resolved from context alone. Arabic dictionaries with vowel marks provide information about the correct pronunciation to both native and foreign Arabic speakers. In art and calligraphy, ḥarakāt might be used simply because their writing is considered aesthetically pleasing.
An example of a fully vocalised (vowelised or vowelled) Arabic from the Basmala:
بِسْمِ ٱللَّٰهِ ٱلرَّحْمَٰنِ ٱلرَّحِيمِ
bismi -llāhi r-raḥmāni r-raḥīmi
In the name of God, the All-Merciful, the Especially-Merciful.
Some Arabic textbooks for foreigners now use ḥarakāt as a phonetic guide to make learning reading Arabic easier. The other method used in textbooks is phonetic romanisation of unvocalised texts. Fully vocalised Arabic texts (i.e. Arabic texts with ḥarakāt/diacritics) are sought after by learners of Arabic. Some online bilingual dictionaries also provide ḥarakāt as a phonetic guide similarly to English dictionaries providing transcription.
The ḥarakāt حَرَكَات , which literally means 'motions', are the short vowel marks. There is some ambiguity as to which tashkīl are also ḥarakāt; the tanwīn, for example, are markers for both vowels and consonants.
The fatḥah ⟨فَتْحَة⟩ is a small diagonal line placed above a letter, and represents a short /a/ (like the /a/ sound in the English word "cat"). The word fatḥah itself (فَتْحَة) means opening and refers to the opening of the mouth when producing an /a/. For example, with dāl (henceforth, the base consonant in the following examples): ⟨دَ⟩ /da/.
When a fatḥah is placed before a plain letter ⟨ا⟩ (alif) (i.e. one having no hamza or vowel of its own), it represents a long /aː/ (close to the sound of "a" in the English word "dad", with an open front vowel /æː/, not back /ɑː/ as in "father"). For example: ⟨دَا⟩ /daː/. The fatḥah is not usually written in such cases. When a fathah placed before the letter ⟨ﻱ⟩ (yā’), it creates an /aj/ (as in "lie"); and when placed before the letter ⟨و⟩ (wāw), it creates an /aw/ (as in "cow").
Although paired with a plain letter creates an open front vowel (/a/), often realized as near-open (/æ/), the standard also allows for variations, especially under certain surrounding conditions. Usually, in order to have the more central (/ä/) or back (/ɑ/) pronunciation, the word features a nearby back consonant, such as the emphatics, as well as qāf, or rā’. A similar "back" quality is undergone by other vowels as well in the presence of such consonants, however not as drastically realized as in the case of fatḥah.
A similar diagonal line below a letter is called a kasrah ⟨كَسْرَة⟩ and designates a short /i/ (as in "me", "be") and its allophones [i, ɪ, e, e̞, ɛ] (as in "Tim", "sit"). For example: ⟨دِ⟩ /di/.
When a kasrah is placed before a plain letter ⟨ﻱ⟩ (yā’), it represents a long /iː/ (as in the English word "steed"). For example: ⟨دِي⟩ /diː/. The kasrah is usually not written in such cases, but if yā’ is pronounced as a diphthong /aj/, fatḥah should be written on the preceding consonant to avoid mispronunciation. The word kasrah means 'breaking'.
The ḍammah ⟨ضَمَّة⟩ is a small curl-like diacritic placed above a letter to represent a short /u/ (as in "duke", shorter "you") and its allophones [u, ʊ, o, o̞, ɔ] (as in "put", or "bull"). For example: ⟨دُ⟩ /du/.
When a ḍammah is placed before a plain letter ⟨و⟩ (wāw), it represents a long /uː/ (like the 'oo' sound in the English word "swoop"). For example: ⟨دُو⟩ /duː/. The ḍammah is usually not written in such cases, but if wāw is pronounced as a diphthong /aw/, fatḥah should be written on the preceding consonant to avoid mispronunciation.
The word ḍammah (ضَمَّة) in this context means rounding, since it is the only rounded vowel in the vowel inventory of Arabic.
The superscript (or dagger) alif ⟨أَلِف خَنْجَرِيَّة⟩ (alif khanjarīyah), is written as short vertical stroke on top of a consonant. It indicates a long /aː/ sound for which alif is normally not written. For example: ⟨هَٰذَا⟩ (hādhā) or ⟨رَحْمَٰن⟩ (raḥmān).
The dagger alif occurs in only a few words, but they include some common ones; it is seldom written, however, even in fully vocalised texts. Most keyboards do not have dagger alif. The word Allah ⟨الله⟩ (Allāh) is usually produced automatically by entering alif lām lām hāʾ. The word consists of alif + ligature of doubled lām with a shaddah and a dagger alif above lām.
The maddah ⟨مَدَّة⟩ is a tilde-shaped diacritic, which can only appear on top of an alif (آ) and indicates a glottal stop /ʔ/ followed by a long /aː/.
In theory, the same sequence /ʔaː/ could also be represented by two alifs, as in *⟨أَا⟩, where a hamza above the first alif represents the /ʔ/ while the second alif represents the /aː/. However, consecutive alifs are never used in the Arabic orthography. Instead, this sequence must always be written as a single alif with a maddah above it, the combination known as an alif maddah. For example: ⟨قُرْآن⟩ /qurˈʔaːn/.
Main article: Wasla (diacritic)
The waṣlah ⟨وَصْلَة⟩, alif waṣlah ⟨أَلِف وَصْلَة⟩ or hamzat waṣl ⟨هَمْزَة وَصْل⟩ looks like a small letter ṣād on top of an alif ⟨ٱ⟩ (also indicated by an alif ⟨ا⟩ without a hamzah). It means that the alif is not pronounced when its word does not begin a sentence. For example: ⟨بِٱسْمِ⟩ (bismi), but ⟨ٱمْشُوا۟⟩ (imshū not mshū). This is because no Arab word can start with a vowel-less consonant (unlike the English school, or skateboard). But when it happens, an alif is added to obtain a vowel or a vowelled consonant at the beginning of one's speech. In English that would result in *ischool, or *iskateboard.
It occurs only in the beginning of words, but it can occur after prepositions and the definite article. It is commonly found in imperative verbs, the perfective aspect of verb stems VII to X and their verbal nouns (maṣdar). The alif of the definite article is considered a waṣlah.
It occurs in phrases and sentences (connected speech, not isolated/dictionary forms):
The sukūn ⟨سُكُونْ⟩ is a circle-shaped diacritic placed above a letter ( ْ). It indicates that the consonant to which it is attached is not followed by a vowel, i.e., zero-vowel.
It is a necessary symbol for writing consonant-vowel-consonant syllables, which are very common in Arabic. For example: ⟨دَدْ⟩ (dad).
The sukūn may also be used to help represent a diphthong. A fatḥah followed by the letter ⟨ﻱ⟩ (yā’) with a sukūn over it (ـَيْ) indicates the diphthong ay (IPA /aj/). A fatḥah, followed by the letter ⟨ﻭ⟩ (wāw) with a sukūn, (ـَوْ) indicates /aw/.
The sukūn may have also an alternative form of the small high head of hāʾ (U+06E1 ۡ ), particularly in some Qurans. Other shapes may exist as well (for example, like a small comma above ⟨ʼ⟩ or like a circumflex ⟨ˆ⟩ in nastaʿlīq).
Main article: Nunation
The three vowel diacritics may be doubled at the end of a word to indicate that the vowel is followed by the consonant n. They may or may not be considered ḥarakāt and are known as tanwīn ⟨تَنْوِين⟩, or nunation. The signs indicate, from left to right, -un, -in, -an.
These endings are used as non-pausal grammatical indefinite case endings in Literary Arabic or classical Arabic (triptotes only). In a vocalised text, they may be written even if they are not pronounced (see pausa). See i‘rāb for more details. In many spoken Arabic dialects, the endings are absent. Many Arabic textbooks introduce standard Arabic without these endings. The grammatical endings may not be written in some vocalized Arabic texts, as knowledge of i‘rāb varies from country to country, and there is a trend towards simplifying Arabic grammar.
The sign ⟨ـً⟩ is most commonly written in combination with ⟨ـًا⟩ (alif), ⟨ةً⟩ (tā’ marbūṭah), ⟨أً⟩ (alif hamzah) or stand-alone ⟨ءً⟩ (hamzah). Alif should always be written (except for words ending in tā’ marbūṭah, hamzah or diptotes) even if an is not. Grammatical cases and tanwīn endings in indefinite triptote forms:
Main article: Shadda
The shadda or shaddah ⟨شَدَّة⟩ (shaddah), or tashdid ⟨تَشْدِيد⟩ (tashdīd), is a diacritic shaped like a small written Latin "w".
It is used to indicate gemination (consonant doubling or extra length), which is phonemic in Arabic. It is written above the consonant which is to be doubled. It is the only ḥarakah that is commonly used in ordinary spelling to avoid ambiguity. For example: ⟨دّ⟩ /dd/; madrasah ⟨مَدْرَسَة⟩ ('school') vs. mudarrisah ⟨مُدَرِّسَة⟩ ('teacher', female).
The i‘jām ⟨إِعْجَام⟩ (sometimes also called nuqaṭ) are the diacritic points that distinguish various consonants that have the same form (rasm), such as ⟨ـبـ⟩ /b/ ب, ⟨ـتـ⟩ /t/ ت, ⟨ـثـ⟩ /θ/ ث, ⟨ـنـ⟩ /n/ ن, and ⟨ـيـ⟩ /j/ ي. Typically i‘jām are not considered diacritics but part of the letter.
Early manuscripts of the Qur’ān did not use diacritics either for vowels or to distinguish the different values of the rasm. Vowel pointing was introduced first, as a red dot placed above, below, or beside the rasm, and later consonant pointing was introduced, as thin, short black single or multiple dashes placed above or below the rasm (image). These i‘jām became black dots about the same time as the ḥarakāt became small black letters or strokes.
Typically, Egyptians do not use dots under final yā’ ⟨ي⟩, which looks exactly like alif maqṣūrah ⟨ى⟩ in handwriting and in print. This practice is also used in copies of the muṣḥaf (Qurʾān) scribed by ‘Uthman Ṭāhā. The same unification of yā and alif maqṣūrā has happened in Persian, resulting in what the Unicode Standard calls "Arabic Letter Farsi Yeh", that looks exactly the same as yā in initial and medial forms, but exactly the same as alif maqṣūrah in final and isolated forms ⟨یـ ـیـ ـی⟩.
At the time when the i‘jām was optional, unpointed letters were ambiguous. To clarify that a letter would lack i‘jām in pointed text (i.e. ⟨ح⟩ /ħ/, ⟨د⟩ /d/, ⟨ر⟩ /r/, ⟨س⟩ /s/, ⟨ص⟩ /sˤ/, ⟨ط⟩ /tˤ/, ⟨ع⟩ /ʕ/, ⟨ل⟩ /l/, ⟨ه⟩ /h/), the letter could be marked with a small v- or seagull-shaped diacritic above, also a superscript semicircle (crescent), a subscript dot (except in the case of ⟨ح⟩; three dots were used with ⟨س⟩), or a subscript miniature of the letter itself. A superscript stroke known as jarrah, resembling a long fatħah, was used for a contracted (assimilated) sin. Thus ⟨ڛ سۣ سۡ سٚ⟩ were all used to indicate that the letter in question was truly ⟨س⟩ and not ⟨ش⟩. These signs, collectively known as ‘alāmātu-l-ihmāl, are still occasionally used in modern Arabic calligraphy, either for their original purpose (i.e. marking letters without i‘jām), or often as purely decorative space-fillers. The small ک above the kāf in its final and isolated forms ⟨ك ـك⟩ was originally an ‘alāmatu-l-ihmāl that became a permanent part of the letter. Previously this sign could also appear above the medial form of kāf, when that letter was written without the stroke on its ascender. When kaf was written without that stroke, it could be mistaken for lam, thus kaf was distinguished with a superscript kaf or a small superscript hamza (nabrah), and lam with a superscript l-a-m (lam-alif-mim).
Main article: Hamza
Although normally a diacritic is not considered a letter of the alphabet, the hamza هَمْزة (hamzah, glottal stop), often stands as a separate letter in writing, is written in unpointed texts and is not considered a tashkīl. It may appear as a letter by itself or as a diacritic over or under an alif, wāw, or yā.
Which letter is to be used to support the hamzah depends on the quality of the adjacent vowels;
Consider the following words: ⟨أَخ⟩ /ʔax/ ("brother"), ⟨إسْماعِيل⟩ /ʔismaːʕiːl/ ("Ismael"), ⟨أُمّ⟩ /ʔumm/ ("mother"). All three of above words "begin" with a vowel opening the syllable, and in each case, alif is used to designate the initial glottal stop (the actual beginning). But if we consider middle syllables "beginning" with a vowel: ⟨نَشْأة⟩ /naʃʔa/ ("origin"), ⟨أَفْئِدة⟩ /ʔafʔida/ ("hearts"—notice the /ʔi/ syllable; singular ⟨فُؤاد⟩ /fuʔaːd/), ⟨رُؤُوس⟩ /ruʔuːs/ ("heads", singular ⟨رَأْس⟩ /raʔs/), the situation is different, as noted above. See the comprehensive article on hamzah for more details.
According to tradition, the first to commission a system of harakat was Ali who appointed Abu al-Aswad al-Du'ali for the task. Abu al-Aswad devised a system of dots to signal the three short vowels (along with their respective allophones) of Arabic. This system of dots predates the i‘jām, dots used to distinguish between different consonants.
Abu al-Aswad's system of Harakat was different from the system we know today. The system used red dots with each arrangement or position indicating a different short vowel.
A dot above a letter indicated the vowel a, a dot below indicated the vowel i, a dot on the side of a letter stood for the vowel u, and two dots stood for the tanwīn.
However, the early manuscripts of the Qur'an did not use the vowel signs for every letter requiring them, but only for letters where they were necessary for a correct reading.
The precursor to the system we know today is Al Farahidi's system. al-Farāhīdī found that the task of writing using two different colours was tedious and impractical. Another complication was that the i‘jām had been introduced by then, which, while they were short strokes rather than the round dots seen today, meant that without a color distinction the two could become confused.
Accordingly, he replaced the ḥarakāt with small superscript letters: small alif, yā’, and wāw for the short vowels corresponding to the long vowels written with those letters, a small s(h)īn for shaddah (geminate), a small khā’ for khafīf (short consonant; no longer used). His system is essentially the one we know today.
The process of automatically restoring diacritical marks is called diacritization or diacritic restoration. It is useful to avoid ambiguity in applications such as Arabic machine translation, text-to-speech, and information retrieval. Automatic diacritization algorithms have been developed. For Modern Standard Arabic, the state-of-the-art algorithm has a word error rate (WER) of 4.79%. The most common mistakes are proper nouns and case endings. Similar algorithms exist for other varieties of Arabic.