So, you've heard about a very structured type of poetry...the sonnet. Now, let's talk about two other kinds:
Blank Verse: Blank verse has no formal rhyme scheme or pattern like a sonnet does. However, it does still keep the iambic pentameter. People wrote in blank verse, because it kept a certain, pleasing beat, or rhythm.
from
William Shakespeare’s Romeo and Juliet where Juliet is going on and on (she’s such a drama queen) about how
she would rather be tossed off a tall
tower, be a villain, walk in snake-infested pits, be chained to bears, or
locked in a crypt, or even get buried with a dead person in a new grave…..instead
of being forced to marry some guy named Paris, instead of her love, Romeo.
...bid me leap, rather than marry Paris,
From off the battlements of yonder tower;
Or walk in thievish ways; or bid me lurk
Where serpents are; chain me with roaring bears;
Or shut me nightly in a charnel-house,
O’er covered quite with dead men’s rattling bones,
With reeky shanks and yellow chapless skulls;
Or bid me go into a new-made grave,
And hide me with a dead man and his shroud;
(Note: This section is also an excellent example of hyperbole, because the girl is out of control in exaggeration with what she'd rather do. It's also an example of verbal irony, because she does get locked in a crypt later on!)
Free Verse: At some point, people got fed up having to fit their poetry in such a formal structure. They decided to free their verse from all those rules. Free verse has no rhyme scheme, and not even iambic pentameter or any other restriction on it. Sure, you can have rhymes or anything else in it, but you're not tied down.
"The Storm" by Vivian Gilbert Zabel
Lightning strikes as thunder roars
Sending war across the skies.
Blackness blankets light of night
Except when fire flashes bright,
Blinding eyes to truth, to right.
Tears of agony rain from irate clouds,
Which smother joy, bringing moans
Of pain, despair, distress,
Leaving open bleeding sores
That never can be healed
Until the battle ends
With God’s peace revealed.
Note: although rhyme is used, there is no rhyme scheme (or pattern).