In English, syllables are the basic units of pronunciation. The pronunciation of any word is divided into individual syllables. Words can be classified as monosyllabic, disyllabic, or polysyllabic based on the number of vowel sounds in their actual pronunciation. Monosyllabic words have only one vowel sound, disyllabic words have two vowel sounds, and polysyllabic words have three or more vowel sounds. The number of vowel sounds in a word is the key factor in distinguishing between these types of words.