Poems come in all forms, but here are a few common types.
The Villanelle. The villanelle is an intricate braiding of 19 lines, many of them repeated, that are divided into about five stanzas.
The Pantoum. The pantoum can be of any length, but it must be divided into four-line stanzas, also called quatrains. The first and last lines of each stanza are always the same and the rhyme scheme is abba.
The Sonnet. Sonnets are always 14 lines long, and the rhythm scheme is typically iambic pentameter. Shakespearean sonnets have a rhyme scheme of abab cdcd efef gg. Petrarchan sonnets have a rhyme scheme of abba abba cde cde.