Primary letters

Primary letters

The Arabic alphabet has 28 basic letters. There are no distinct upper and lower case letter forms.

Many letters look similar but are distinguished from one another by dots (iʿjam) above or below their central part, called rasm. These dots are an integral part of a letter, since they distinguish between letters that represent different sounds. 

For example, the Arabic letters transliterated as b and t have the same basic shape, but b has one dot below, ب , and t has two dots above, ت .

Both printed and written Arabic are cursive, with most of the letters within a word directly connected to the adjacent letters. 

Unlike cursive writing based on the Latin alphabet, the standard Arabic style is to have a substantially different shape depending on whether it will be connecting with a preceding and/or a succeeding letter, thus all primary letters have conditional forms for their glyphs, depending on whether they are at the beginning, middle or end of a word, so they may exhibit four distinct forms (initial, medial, final or isolated). 

However, six letters have only isolated or final form, and so force the following letter (if any) to take an initial or isolated form, as if there were a word break.
Some letters look almost the same in all four forms, while others show considerable variation. 

Generally, the initial and middle forms look similar except that in some letters the middle form starts with a short horizontal line on the right to ensure that it will connect with its preceding letter. 

The final and isolated forms, are also similar in appearance but the final form will also have a horizontal stroke on the right and, for some letters, a loop or longer line on the left with which to finish the word with a subtle ornamental flourish. In addition, some letter combinations are written as ligatures (special shapes), including lām-ʼalif.

Six letters ( أ,د,ذ,ر,ز,و ) are not connected to the letter following them, therefore their initial form matches the isolated and their medial form matches the final.

Isolated Contextual forms Name Translit. Phonemic Value (IPA) End Middle Beginning
ا
ا
ا
ا
ʾalif
ʾ / ā
various, including /aː/ ب ب ب ب bāʾ B /b/, also /p/ in some loanwords
ت
ت
ت
ت
tāʾ
T
/t/ ث ث ث ث ṯāʾ ṯ /θ/
ج
ج
ج
ج
Ǧīm
ǧ (also j)
[ dʒ~ʒ~ɡ ] ح ح ح ح ḥāʾ ḥ /ħ/
خ
خ
خ
خ
ḫāʾ
ḫ (also kh, x)
[ x~χ ] د د د د Dāl D /d/
ذ
ذ
ذ
ذ
ḏāl
ḏ (also dh, ð)
/ð/ ر ر ر ر rāʾ R /r/
ز
ز
ز
ز
Zāy
Z
/z/ س س س س sīn S /s/
ش
ش
ش
ش
šīn
š (also sh)
/ʃ/ ص ص ص ص ṣād ṣ /sˁ/
ض
ض
ض
ض
ḍād
ḍ
/dˁ/ ط ط ط ط ṭāʾ ṭ /tˁ/
ظ
ظ
ظ
ظ
ẓāʾ
ẓ
[ ðˁ~zˁ ] ع ع ع ع ʿayn ʿ /ʕ/
غ
غ
غ
غ
ġayn
ġ (also gh)
/ɣ/ (/ɡ/ in many loanwords, <ج> is normally used in Egypt) ف ف ف ف fāʾ F /f/, also /v/ in some loanwords
ق
ق
ق
ق
qāf
Q
/q/ ك ك ك ك kāf K /k/
ل
ل
ل
ل
lām
L
/l/, (/lˁ/ in Allah only) م م م م mīm M /m/
ن
ن
ن
ن
nūn
N
/n/ ه ه ه ه hāʾ H /h/
و
و
و
و
wāw
w / ū / aw
/w/ / /uː/ / /au/, sometimes /u/, /o/ and /oː/ in loanwords ي ي ي ي yāʾ y / ī / ay /j/ / /iː/ / /ai/, sometimes /i/, /e/ and /eː/ in loanwords

Further notes:
Arabic currently uses a diacritic sign, ء , called hamza,to denote the glottal stop, written alone or with a carrier:
o alone: ء ;
o with a carrier: إ, أ (above or under a ʾalif), ؤ (above a wāw), ئ (above a dotless yāʾ or yāʾ hamza).

Letters lacking an initial or medial version are never linked to the letter that follows, even within a word. The hamza has a single form, since it is never linked to a preceding or following letter. However, it is sometimes combined with a wāw, yāʾ, or ʾalif, and in that case the carrier behaves like an ordinary wāw, yāʾ, or ʾalif.

In academic work, the glottal stop [ʔ] is transliterated with the right half ring sign (ʾ), while the left half ring sign (ʿ) represents a different letter, with a different pronunciation, called ʿayin.

Modified letters
The following are not individual letters, but rather different contextual variants of some of the Arabic letters. Conditional forms Name Translit. Phonemic Value (IPA) Isolated Final Medial Initial
آ

آ
آ
آ
ʾalif madda
ʾā
/ʔaː/
ة

ة
tāʾ marbūṭa
h or t / h / ẗ
/a/, /at/
ى

ى
ʾalif maqṣūra
ā / ỳ
/aː/

Ligatures
The only compulsory ligature for fonts and text processing in the basic Arabic language alphabet are ones for lām + ʼalif. All other ligatures (yāʼ + mīm, etc.) are optional. Example to illustrate it is below.
 (initial or isolated) lām + ʼalif (lā /laː/):
لا
(final or medial) lām + ʼalif (lā /laː/):
لا

Another interesting ligature in the is the special code for glyph for the ligature Allāh (“God”),
الله

This latter ligature code again is a work-around for the shortcomings of most text processors, which are incapable of displaying the correct vowel marks for the word Allāh, because it should compose a small ʼalif sign above a gemination šadda sign. Compare the display above to the composed equivalents below (the exact outcome will depend on your browser and font configuration):
lām, (geminated) lām (with implied short a vowel, reversed) hāʼ : لله
alif, lām, (geminated) lām (with implied short a vowel, reversed) hāʼ : الله