A stanza is a grouped set of lines in a poem, similar to a paragraph in prose. Stanzas often have a specific number of lines and can follow a particular rhyme scheme or rhythm. They help organize thoughts and ideas, making the poem easier to read and understand. Stanzas can vary in length and structure, with common types including couplets (two lines), quatrains (four lines), and sestets (six lines). Poets use stanzas to create visual breaks in the text, emphasize certain themes, or convey emotions, enhancing the overall impact of the poem.