To understand word stress, we have to understand syllables. Words have one or more syllables. A syllable is a unit of pronunciation. It consists of either a vowel sound alone or a vowel and one or more consonant sounds. Notice that (with a few rare exceptions) every syllable contains at least one vowel (a, e, i, o or u) or vowel sound. Every word is made from syllables. Each word has one, two, three or more syllables.