Vowels
The main 30 characters of the Tamil Script can be divided in two types: 12 vowels (உயிரெழுத்து｢uyireḻuttu｣) and 18 consonants (மெய்யெழுத்து｢meyyeḻuttu｣)
From English Grammar you already know five vowels: a, e, i, o, u. In Tamil you have these vowels as well, but they do exist in a shorter and a longer version:
அ｢a｣ and ஆ｢ā｣
இ｢i｣ and ஈ｢ī｣
உ｢u｣ and ஊ｢ū｣
எ｢e｣ and ஏ｢ē｣
ஒ｢o｣ and ஓ｢ō｣
Since all letters are a combination of 12 vowels and 18 consonantsevery sound exists in a longer and shorter version. That might be more lettersto learn at the first sight, but in the end it is very handy because you willalways be able to tell whether you have to pronounce a syllable long or short.
So the 5 vowels each in two versions already make 10 letters. Additionally, Tamil counts two diphthongs as vowels as well.
A diphthong is a combination of two adjacent vowels within a single syllable. In English for example you have words like loud or haunt.
In Tamil, you have ஐ｢ai｣ and ஔ｢au｣ which are similar to the diphthongs from the German language. ஔ｢au｣ sounds like the ｢ou｣ in the English word loud. And ஐ｢ai｣ sounds like the ｢ie｣ in words like to lie.
The two diphthongs only exist in the shorter version.
That makes 5x2 vowels and 2 diphthongs that can be combined with 18 consonants to create 216 characters.
The matrix of the Tamil script writes the vowels in the following order: