In the generic sense, klon (กลอน, [klɔ̄ːn]) originally referred to any type of poetry. In the narrow sense it refers to a more recently developed form where a stanza has four wak, each with the same number of syllables. It is usually considered an original Thai form.[4] The klon metres are named by the number of syllables in a wak, e.g. klon hok (กลอนหก, [klɔ̄ːn hòk]) has six syllables per wak (hok means six). All metres have the same rhyming scheme, and there are also requirements on the tone of the final syllable of each wak. The klon is also divided into several types according to their manner of composition, with klon suphap (กลอนสุภาพ, [klɔ̄ːn sù.pʰâːp]) being the basic form.
The following plan shows the structure of klon suphap (two stanzas) in the most common eight-syllable variety, which was employed extensively by Sunthorn Phu, and is the most common form of the Rattanakosin period. The letters in parentheses represent alternative rhyming syllables. In practice, occasional wak with seven or nine syllables are also acceptable.