Iambic pentameter is a type of poetical meter. It is composed of 5 iambs, an iamb being a metrical unit consisting of an unstressed syllable followed by a stressed one. (Note that all of Shakespeare's plays are written mostly in unrhymed iambic pentameter verse - his sonnets are written in rhymed iambic pentameter.) The stress pattern in a line of ip verse is therefore: _^ _^ _^ _^ _^.