Wow.
That was interesting.
Each letter can have up to 4 “forms” depending on whether it stands alone, or is used at the beginning, or in the middle, or at the end of a word.The article says there are 28 letters - but with all those forms for each letter, it’s no wonder it always looked to me like written Arabic must have had hundreds of different letters.
Hebrew has different forms for certain letters if they come at the end of a word. Arabic takes it to a whole different level.