Thai words has a complicated relationship between spelling and their pronunciation. Many of the letters today have different sounds than when they were first used. While many Thai words have tone markers that show the tone of a word, many do not. However the word will still have a tone, and for words that do not have tone markers, one can still figure out the tone by the class of consonant (high, middle, or low), whether the syllable is a live or dead, syllable, and the length of the vowel. While the different classes of consonants made different phonemes, or distinct sounds, in the past, they now are set apart by which tones the words have.