The Arabic alphabet is filled with diacritical marks. The removal or addition of any mark to a word may change its entire meaning and pronunciation. Adding a dot on the first letter of the word Arab will change its meaning to Westerner. The diacritical dot replaces the first letter with another letter, therefore changing its meaning.
This is me in transition, read right to left, عربي (Arab) to غربي (Westerner) by simply adding a dot.