After the unification of the Lao principalities (meuang) in the 14th century, the Lan Xang monarchs commissioned their scholars to create a new script to write the Lao language. The scholars probably modelled the alphabet on the the Old Khmer script, which was itself based on Mon scripts.
Direction of writing: left to right in horizontal lines
Syllables are based around consonants. Vowels are indicated with diacritics which can appear above, below or around the consonant letters. When they occur on their own or at the beginning of a word, vowels are attached to the glottal stop symbol (the final letter in the third row of consonants).
Lao is a tonal language with 6 tones. The tone of a syllable is determined by a combination of the class of consonant, the type of syllable (open or closed), the tone marker and the length of the vowel (see below).
For some consonants there are multiple letters. Originally they represented separate sounds, but over the years the distinction between those sounds was lost and the letters were used instead to indicate tones. Various offical reforms of the Lao script have reduced the number of duplicate consonants.