Learning Arabic can be fun.. In the initial learning, a marking stroke is put on the letters to identify the sound. Let see an example used in the following word.
1. درس - Arabic is written from right to left, in the example given, there are 3 letters.
د - dal -
ر - ro
س - sin
in the above word, for beginner, a stroke(or marking) will be put on top of each letters so show that it sound like having a letter "a " after the vowel... so it will sound.....da ....ra...sa... ( the sound cannot be directly translated into english words). In Arabic the stroke on top is called 'fathah'
These markings help readers to read the Arabic. For that reason, the readers of Quran can read it, and listeners will not know if the reader is an arabic or not.
2. Example 2 --- درب .
The second word is da...ri...ba
You may ask why can't it be different sound. The answer is simple.... That is how it should sound ... Like the word "I" in English, everyone knows how it should sound except those who do not know English.
The second stroke is at the bottom, giving sound like vowel followed by the letter i.. The stroke at the bottom is called kasrah.
د .... stroke on top -- like +a ... sound da
ر ..... stroke at the botton... like + i .... sound ri
ب .... stroke at the top like + a ......sound ba