Rules for what speech sound can occur in a language and how those speech sounds combine to create words is known as phonotactics. An example would be that phonotactics guide the number of syllables that are permissible in words, what are permissible as word positions for vowels and consonants, the type of consonants and vowels that can combine in syllables, the presence/absence of consonant clusters at the beginning or end of syllables, and the number, type, and sequence of consonants that can form a consonant cluster. Additionally, the presence or absence of lexical tones and harmony patterns in included. Phonotactics give rise to a variety of parts that are permissible in a language including vowels, consonants, word shapes and lengths, and syllable shapes and consonant clusters.