Iambic pentameter is a metrical line consisting of five iambs—five feet each made of an unstressed syllable followed by a stressed one. The pattern produces a ten-syllable line with a rising rhythm.

It is the most common meter in English poetry and drama from the Renaissance onward. Shakespeare’s plays and sonnets, Milton’s epics, and countless later poems are built on it. The form is flexible: stresses can be inverted, syllables elided, and extra unstressed syllables added, so that the line ranges from strict regularity to near-speech. The underlying pulse remains audible beneath the variations.

Iambic pentameter suits English because the language naturally alternates stressed and unstressed syllables. It can support elevated rhetoric or quiet reflection. Blank verse is simply unrhymed iambic pentameter; heroic couplets are rhymed pairs of such lines. Mastery of the meter has long been considered fundamental to the craft of English verse.

Five rising feet to the line give English poetry its most familiar measure.