Type of writing system: syllabic alphabet consisting of 44 basic consonants, each with an inherent vowel: [o] in medial position and [a] in final position. The [a] is usually found in words of Sanskrit, Pali or Khmer origin while the [o] is found native Thai words. The 18 other vowels and 6 diphthongs are indicated using diacritics which appear in front of, above, below of after the consonants they modify.
Direction of writing: left to right in horizontal lines.
8 of the letters are used only for writing words of Pali and Sanskrit origin.
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.
Thai is a tonal language with 5 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. More details.
There are no spaces between words, instead spaces in a Thai text indicate the end of a clause or sentence.
Consonants are divided into three classes: low (เสียงต่ำ), mid (เสียงกลาง) and high (เสียงสูง) , which help to determine the tone of a syllable.
The sounds represented by some consonants change when they are used at the end of a syllable (indicated by the letters on the right of the slash). Some consonants can only be used at the beginning of a syllable.
Duplicate consonants represent different Sanskrit and Pali consonants sounds which are pronounced identically in Thai.
The letter o ang acts as a silent vowel carrier at the beginning of words that start with a vowel.
The names of the consonants are acrophonic and intended to help with learning them.