Historically, iambic pentameter is the workhorse of formal poetry (and that’s only one type of meter). Regular poetic meter is a pattern of a two-or-three-syllable units (feet) repeated in a line of verse. As with music, our ear likes the predictability of rhythm: if the beat is broken unexpectedly, the listener stumbles.
But human language does not follow metrical rules. If the poet plays the meter loosely to blend it with the natural cadence of speech, the line hooks the reader, whose brain (subliminally) can relate to familiar rhythms and expressions. It’s harder for the listener to get a foothold into a rigid monotonous line where the feet move in hypnotic lockstep. The goal is not to induce coma in the reader.
Meter is pliable—something for a poet to engineer, not follow slavishly. We’ll talk about how to bend it to your will.