The style in which a piece of literature is written, such as a novel, short story, play, dramatic monologue, or sonnet, is referred to as its form. The genre in which a work is written is also incorporated in its form. Examples include gothic and comedic styles. Form is important in defining the voice of a writer. There are two types of forms: specific and general. Specific forms are used for a limited number of topics or themes. They tend to be rigid structures with certain requirements, such as symmetry or regular rhyme or meter. For example, a sonnet has 14 lines of three quatrains and one final couplet. A villanelle is another popular sonnet-like form; it has five tercets and one final quatrain. Many other poems follow similar patterns as these ones. General forms are more flexible than specific forms and can be used for various topics or subjects. Some common general forms are ballads, blues songs, choruses, hymns, limericks, parodies, sonnets, and villanelles. In addition to their structure, forms often have additional features that define them as particular types of poetry. These features include formal qualities, such as elegance or simplicity; emotional qualities, such as sadness or joy; or philosophical qualities, such as reason or intuition.