The Arabic alphabet is similar to the Hebrew alphabet, in that it is really an abjad. This refers to the fact that short vowels[?] are not written in most books and periodicals, so one must infer these vowels from context. This situation is ameliorated by the fact that Semitic languages put much of their meaning in consonants and long vowels, which are written.
Arabic writing is a joined-up script, rather than a succession of individual glyphs. Amongst other consequences, this means that the form of Arabic letters is influenced by their context.
Doubled consonants are indicated with a tashdeed (a symbol which looks like a letter w) over the Arabic letter.
Arabic Alphabet in Unicode
و ى ي
Old letters: ٮ ٯ
ﷺ (Sall-allahu alayhi wasallam) - ﷲ (Allah)