Thai is a Unicode block containing characters for the Thai, Lanna Tai, and Pali languages. It is based on the Thai Industrial Standards 620-2529 and 620-2533.

Thai script (Thai: อักษรไทย; rtgs: akson thai; ʔàksɔ̌ːn tʰāj) is used to write the Thai language and other languages in Thailand. It has 44 consonant letters (Thai: พยัญชนะ, phayanchana), 15 vowel symbols (Thai: สระ, sara) that combine into at least 28 vowel forms, and four tone diacritics (Thai: วรรณยุกต์ or วรรณยุต, wannayuk or wannayut). Although commonly referred to as the «Thai alphabet», the character set is in fact not a true alphabet but an abugida, a writing system in which each consonant may invoke an inherent vowel sound. In the case of the Thai script this is an implied 'a' or 'o'. Consonants are written horizontally from left to right, with vowels arranged above, below, to the left, or to the right of the corresponding consonant, or in a combination of positions. Thai has its own set of Thai numerals which are based on the Hindu Arabic numeral system (Thai: เลขไทย, lek thai), but the standard western Hindu-Arabic numerals (Thai: เลขฮินดูอารบิก, lek hindu arabik) are also commonly used.