A haiku is a form of tercet, which is a three-lined stanza or poem. However, haiku has a specific structure and thematic focus that distinguish it from other tercets. Traditionally, a haiku follows a syllable pattern of 5-7-5 across its three lines and often captures moments of natural beauty, seasons, or fleeting aspects of the human experience, offering a philosophical or emotional insight. While all haikus are tercets because they consist of three lines, not all tercets are haikus, as tercets can vary widely in form, theme, and syllable count.