As with the above-mentioned works (epic poems), poetry can be longer than most novels or super short like William Carlos Williams' The Red Wheelbarrow. Poems can cover every subject or personal thought, idea, or emotion that a writer chooses to put to paper. A poem can be funny, serious, morbid, political, breezy, musical, etc. A poem can be composed specifically for public consumption, or written for completely selfish reasons: a window into the soul of a person who never thought their writing would even bee seen by the eyes of anyone else except them.
You don't have to be a master of interpreting poetry to enjoy it. You do not have to be a literary master to write a poem; all you have to do is be willing to put pen to paper, or tap a few keys to create your personal art. Find your ideal poem in a book or in your own head, just don't think poetry is beyond your reach. Read it, write it, or do a little bit of both for good measure!
but so is the blood spilled
from Juliet's happy dagger.