I want to know about vowelled and non vowelled letters in Holy Qur'an.

Question
Assalamu alaikum.
I want to know about vowelled and non vowelled letters in Holy Qur'an.

Answer
Wa alaikum assalaam wa rahmatullahi wa barakatuh.

Every Arabic letter, outside of the pure alif, can take a vowel or have the absence of a vowel-called sukoon in Arabic.
The three vowels are the fath, the kasrah, and the dhammah.  The sukoon means there is no vowel, that the letter is pronounced with no accompanying mouth and jaw movement.  The mouth and jaw movement which happens with vowels are:
1. opening of the mouth- with the fath
2. lowering of the jaw-with the kasrah
3. circling of the lips- with the dhammah

The shaddah, which is the shape of a very small seen over the letter with a vowel means the letter is pronounced as two of the same letter.  The first letter of the doubled letter in a shaddah has a sukoon, and the second is pronounced with the vowel written with the shaddah mark.  An example of this is the ra' in the word: .
This link explains the vowels quite well: http://web.uvic.ca/hrd/hist455/vowels/vowels_pres.htm, but the English written pronunciation of the words in the chart in the link and the explanation of the sounds of the vowels do not correspond accurately to the correct sounds of the vowels in the proper recitation of the Qur'an. 

Please also see:
http://www.abouttajweed.com/the-mechanism-for-the-formation-of-letters/the-mechanism-of-the-formation-of-letters-part.html

http://www.abouttajweed.com/the-mechanism-for-the-formation-of-letters/the-mechanism-of-the-formation-of-letters-pa.html