These are the 12 vowel letters in Tamil. They are usually only found at the start of a word.
Mey Ezhuthu (மெய் எழுத்துக்கள்)
These are the 18 consonant letters in Tamil. They represent consonant sounds that need to be combined with vowels to form complete syllables. The consonant alone has a muted sound.
Ayudha Ezhuthu (ஆயுத எழுத்து)
This is the special letter 'ஃ' (aytham) in Tamil. It represents a glottal stop sound and is used in certain Tamil words. It's neither a vowel nor a consonant but has its own unique category.
Uyir Mey Ezhuthu (உயிர்மெய் எழுத்துக்கள்)
These are compound letters formed by combining consonants (mey) with vowels (uyir). Each consonant can combine with each of the 12 vowels to create different syllables. This creates the majority of Tamil script combinations used in writing.
Vadamozhi Ezhuthu (வடமொழி எழுத்துக்கள்)
These are Sanskrit-derived letters used in Tamil to write words borrowed from Sanskrit. They include special consonants like ஸ், ஜ், ஷ், ஹ், and compound letters like க்ஷ் and ஸ்ரீ that don't exist in pure Tamil but are needed for Sanskrit loanwords.