A tercet is a poetic unit of three lines, whether as a stanza or as a complete poem, that can be rhymed or unrhymed, metered or unmetered. It is less popular than the couplet (a two-line stanza) or the quatrain (a four-line stanza) . The pace of a tercet is often slower, lending itself to a more somber tone. Examples of tercet forms include English-language haiku, poetic triplet, enclosed tercet, terza rima, villanelle, and Petrarchan sonnet. Tercets can be used to deliver three important lines in a group or to slow the reader down and provide them with the opportunity to view the three lines together for a particular reason.