Learning Letters - Vowels
With Tibetan letters, the vowels are marked with a sign above or below the root letter. To take the མ་ MA letter, if you add a line above, མེ་, it becomes ME (fire). If you add this sign above, མི་, it becomes MI (human, or a negation particle). If you have this, མོ་, it is MO (divination system). Finally, with this sign, མུ་ , you have MU (border.)
Note that the same system is true for all other letters, examples: ལོ། LO (age), ནི། NI (as for), and so on. The signs above or below turns the default vowel, A-based, into a specific vowel. So if you learn these additional four vowels, you know all the five Tibetan vowels.
See if you recognize the various vowels in the Tibetan text below:
།བླ་མ་དེས།དི་ལྟར་བརྗོད་དེ།
ཀྱོད་ཀྱིས་བྱངཆུབ་ཏོ་སྨོན་ལམ་བྲབ་བས།
བདག་ལས་བྱང་ཆུབ་སེམས་དཔའི་ཚུལ་ཁྲིནམས་ཀྱི་བསླབ་པ་འཛིན་པར་འདོད་དམ་ཞེས་པ་ཡང་གསུམ་མོ།