Vowels
 
  There are two types of vowels used in Persian, visible and invisible.
   
  Visible Vowels:
  These are part of the alphabet which are primiraly used as consonants but can take up a secondary task as vowels, these are:
  (alef): As a vowel it is used for the sound 'ā' ('aa') as in "art"
  (vāv): As a vowel it is used for the sound 'oo' as in "tour"; as a consonant it is used as the letter 'v'
  (yeh): As a vowel it is used for the sound 'ee' as in "breeze", as a consonant it is used as the letter 'y'
   
  Invisible Vowels:
  These vowel signs, in my opinion, are the most difficult part of the alphabet for the beginners. The reason being that they are not part of the alphabet and are often omitted in writings. They are simply signs that are placed above or under a letter to create an appropriate sound. There are four vowel signs (invisible vowels):
  called zebar or fat-he: placed above a letter and sounds like 'a' as in "bad"
  called zir or kasre: placed under a letter and sounds like 'e' as in "bed"
  called zammeh: placed above a letter and sounds like 'o' as in "Bonn"
  called sokun: placed above a letter to indicate a pause in the sound as in "sand"