Meter

You cannot escape meter. It is in all writing, all speaking, and whether you do it intentionally or not, it is always there in your work.

Meter is the pattern of stressed and unstressed syllables in your words.
For the Roman poets, for example, meter was everything. Catullus, my favorite poet, wrote hendecasyllabic poetry. Shakespeare wrote most of his work in iambic pentameter. From Twelfth Night:

If music be the food of love, play on;

If you over exaggerate each stressed syllable, you can hear it. da DA, da DA…

If music be the food of love, play on;

You can hear it now, the beat of the words.

Iambs are only one of many patterns of stressed and unstressed syllables. There are also dactyls, spondees and pyrrhic feet.

You will hear meter as you read aloud during editing. Particularly when a misplaced word sticks out. Breaking the meter has an effect on the ear, and can be used intensionally for emphasis or sometimes to the detriment of the line.

When rhyme started to fall out of favor, a form called Blank Verse rose. This is verse that retains a strict meter pattern, but has no rhyme (or at least does not require it). Lines would have a set number of syllables, stresses a certain pattern.

Structure, it seems was an important part of how poetry was defined for a long time.

When you write free verse (or prose, or blog posts, or even tweets), meter is both present, and in the background. You aren’t writing it to a set pattern, but it will still have an effect on the poem as a whole.

And I am not suggesting you need to scan your poetry, marking stressed and unstressed, looking for patterns–but I will suggest you should be able to. And as you read to edit, if you have a word that sticks out, but aren’t sure why, see if it fits the beat.