What poetic meter of five iambic feet per line was famously used by Shakespeare?

The poetic meter of five iambic feet per line famously used by Shakespeare is iambic pentameter.

An iamb is a two-syllable unit with an unstressed syllable followed by a stressed one: da-DUM. “Pentameter” comes from the Greek word for five, so a regular line contains five such feet, typically ten syllables: da-DUM da-DUM da-DUM da-DUM da-DUM.

Shakespeare used iambic pentameter extensively in his plays and sonnets, especially in unrhymed blank verse. It gave dialogue a flexible, speech-like rhythm while providing an underlying poetic structure. Writers could vary the pattern with extra syllables, reversed stresses, or pauses for dramatic effect.

A common mix-up is treating iambic pentameter as a Shakespeare-only invention. Geoffrey Chaucer helped establish the meter in English during the 14th century, and later poets including John Milton, John Keats, and William Wordsworth used it. Shakespeare’s fame comes from the remarkable variety and dramatic naturalness he brought to it.