In Thai, the 42 consonants can be subdivided into 3 groups: high, medium and low class. This determines the tone of a word.
Without a tone marker it is the type of syllable that defines the tone. A dead syllable has an ending and after that ending it is not possible to extend the sound. Dead syllables have either a short or long vowel.
Live syllables end with a long vowel, Á, ¹, § or similar sounds. Dead syllables end with a short vowel, », À, ·, ¤, ¢ or similar sounds.
Remember that in Thai consonants can change their sound depending if they are at the start or end of the word.
Shown using the "dead" consonant Í. Strictly speaking, the last two markers mai dtree and mai jutawah are only used with middle class consonants.