The hokku (also known as "haikai") became recognized as the haiku late in the nineteenth century, when it was stripped of its original role of commencing a succession of verses. Today, the name "haiku" refers to any poem that uses the three-line, 17-syllable pattern, including the older hokku. In addition to being poetic forms, haikus are also used in art and music. They have been popular subjects for artists since at least the 1920s, when they began appearing in print advertisements. In music, they are often used by poets or musicians as a means of promoting new products or services. For example, someone might write a haiku about using a product, which is then set to music with lyrics added by another artist. There are even musical groups named after the form, such as the 1960s group The Hokksins. Although they were originally conceived as short poems, modern haikus can be longer than three lines. Many traditional ones consist of five, seven, or nine syllables, but many others have been written using different numbers of syllables and different types of words. What all haikus have in common is that they use the standard vocabulary of English, although some poets may make extensive use of colloquialisms to achieve unique effects. There are several schools of thought regarding the origin of the haiku. Some believe them to be ancient Japanese poetry, while others claim they are based on Chinese poems.