Certain minority languages such as Saurashtra, Badaga, Irula and Paniya are also written in the Tamil script.

[6] The Tamil script has 12 vowels (உயிரெழுத்து, uyireḻuttu, "soul-letters"), 18 consonants (மெய்யெழுத்து, meyyeḻuttu, "body-letters") and one special character, the ஃ (ஆய்த எழுத்து, āytha eḻuttu).

In addition, according to Iravatham Mahadevan, early Tamil Brahmi used slightly different vowel markers, had extra characters to represent letters not found in Sanskrit and omitted letters for sounds not present in Tamil such as voiced consonants and aspirates.

[8] Inscriptions from the 2nd century use a later form of Tamil-Brahmi, which is substantially similar to the writing system described in the Tolkāppiyam, an ancient Tamil grammar.

By the 8th century, the new scripts supplanted Vaṭṭeḻuttu in the Pallava and Chola kingdoms which lay in the north portion of the Tamil-speaking region.

The scribe had to be careful not to pierce the leaves with the stylus while writing because a leaf with a hole was more likely to tear and decay faster.

The puḷḷi (ஂ) did not fully reappear until the introduction of printing, but the marker kuṟṟiyal-ukaram (ஃ) never came back for this purpose into use although its usage is retained in certain grammatical conceptual words whereas the sound itself still exists and plays an important role in Tamil prosody.

A separate set of characters appears for these sounds when the Tamil script is used to write Sanskrit or other languages.

The order of the alphabet (strictly abugida) in Tamil closely matches that of the nearby languages both in location and linguistics, reflecting the common origin of their scripts from Brahmi.

Combinations of consonants with ஃ (ஆய்த எழுத்து, āyda eḻuttu, equivalent to nuqta) are occasionally used to represent phonemes of foreign languages, especially to write Islamic and Christian texts.

[16][17] The Unicode Standard uses superscripted digits for the same purpose, as in ப² pha, ப³ ba, and ப⁴ bha.

Using the consonant 'k' as an example: The special letter ஃ, represented by three dots, is called āyta eḻuttu or aḵ.

It originally represented an archaic Tamil retention of the Dravidian sound ḥ, which has been lost in almost all modern Dravidian languages, and in Tamil traditionally serves a purely grammatical function, but in modern times it has come to be used as a diacritic to represent foreign sounds.

It also served before palm leaves became the primary writing medium for words ending with an inherent consonsant-vowel u as a pronouncing rule for a short u, called – Tamil: குற்றியலுகரம், romanized: kuṟṟiyal-ukaram, lit.

Another archaic Tamil letter ஂ, represented by a small hollow circle and called Aṉuvara, is the Anusvara.

This makes it necessary to reorder when converting from one encoding to another; it is not sufficient simply to map one set of code points to the other.

Efforts to unify the Grantha script with Tamil have been made;[16][20] however the proposals triggered discontent by some.

[24] Although discouraged by the ICTA of Sri Lanka,[25] the proposal was recognized by the Government of Tamil Nadu[26] and were added to the Unicode Standard in March 2019 with the release of version 12.0.

Each code point representing a similar phoneme is encoded in the same relative position in each South Asian script block in Unicode, including Tamil.

Unicode 5.1 also has a named sequence for the Tamil ligature SRI (śrī), ஶ்ரீ, written using ஶ (śa).