In Thailand and Myanmar, the script is often referred to as Lanna script (Thai: อักษรธรรมล้านนา RTGS: Akson Tham Lan Na; Burmese: လန်နာအက္ခရာ; MLCTS: Lanna Akhkara) in relation to the historical kingdom of Lan Na situating in the Northern region of modern day Thailand and Kyaingtong, Shan state in Myanmar.

[6] Tai Tham script is traditionally written on a dried palm leaf as a palm-leaf manuscript.

It is spoken by nearly 6 million people in Northern Thailand and several thousand in Laos of whom few are literate in Lanna script.

There are 120,000 speakers of Khün for which Lanna is the only script.The Tai Tham script shows a strong similarity to the Mon script used by the Mon kingdom of Haripunjaya around the 13th century CE, in the present-day Lamphun Province of Northern Thailand.

The oldest known document containing the Tai Tham script is dated to 1376 CE and was found in Sukhothai.

The Tai Tham script was adapted to write vernacular languages not later than the 15th century CE, most probably in Chiang Mai, in the Lan Na Kingdom.

[8] The script spread from Lan Na to surrounding areas such as modern day Laos, Isan, Shan State and Sipsong Panna.

Religious instructional materials and prayer books dedicated to the laity were written in Tai Noi instead.

Most of the script is recorded on palm-leaf manuscripts, many of which were destroyed during the 'Thaification' purges of the 1930s; contemporaneously this period of Thai nationalisation also ended its use as the primary written language in Northern Thailand.

[11] Although no longer in use in Isan, the alphabet is enjoying a resurgence in Northern Thailand, and is still used as the primary written script for the Tai Lü and Tai Khün languages spoken in the 'Golden Triangle' where Thailand, Laos, Burma and southern China meet.

In the Unicode input method, sakot sign (U1A60) (◌᩠) is used to trigger the subjoined forms.

In some cases, an additional phoneme /l/ may be added with the initial consonant pronounced as a half-syllable.

Class Consonant cluster with medial Ra does not change the sound of /t͡ɕ/ and /s/, but an additional phoneme /l/ is often added.

Despite the difference in tone quality between Northern Thai, Tai Khuen, Thai, and Lao; equivalent words in each language are, in large part, marked with the same (or equivalent) tone mark.

Tone mark conjugation in Tai Tham follows the same model used for Thai script.

Consonants in each class are combined with these tone marks to give a different tonal pattern.

However, these three new tone marks aren't used in Lanna spelling convention and even in Khuen, they are rarely used.

Hence, by combining the consonant classes and the system of checked–unchecked syllables, the full tone conjugation table can be constructed as shown below.

[ḷa] Tai Tham script was added to the Unicode Standard in October, 2009 with the release of version 5.2.

The Unicode block for Tai Tham is U+1A20–U+1AAF: Supports for Tai Tham Unicode font in Microsoft Windows and Microsoft office are still limited[38] causing the widespread use of non-Unicode fonts.

Fonts published by the Royal Society of Thailand and Chiang Mai University are also non-Unicode due to this problem and to maximize the ability to transcribe and display the ancient Tai Tham text, which frequently contains various special ligatures and symbols not supported by Unicode.

In recent years, many Tai Tham Unicode fonts have been developed for web display and communications via smart phones.

[41] However, the current version of this font still fails to display Tai Tham text correctly.