What is a poem?

Someone recently claimed my writing was too metaphoric and vague to be comprehensible, and hence termed it 'poetic'. I am not a trained literary critic, so the opinions here and in the pieces that will follow are obviously not those of an experienced observer. They are just impressions of what I like and dislike about certain poems. (And hopefully they will explain why I don't agree with calling a vague, incomprehensible piece of writing 'poetic'!)

In trying to answer the "What is a poem?" question the way I see it, I found it easier to begin with what I think is NOT a poem. I don't think a poem is a string of rhyming words. Likening your girlfriend or lover to a blooming springtime in an ABAB rhyme scheme does not always qualify as poetry. Unless you're Tennyson or Keats, that usually ends up being a string of pretty words held together by vague sentiment. (According to me, it works for them for different reasons, and I'll get to that later).

I am also not a fan of overly confessional poems. Grim reality and the underside of life can be portrayed effectively, if not beautifully. Teenage thoughts of suicide and how the world sucks are better left to people who have grown past them enough to articulate effectively. (Paul Simon in 'I am a rock', for example).

For a poem to be effective, it must be:

Strong: Strong images, a single (or few) emotions. It has only a few words, so each one must stand for something.

Bright: Sharp, bright words that stand out are essential. A poem that squanders its breath on decision-making is dead. "I was looking at this gorgeous sunset, it reminded me of my ephemeral youth which will dissolve into the world's apocalyptic end" - A good poem picks ONE thread there, not all three.

And true: Any poem worth sharing is true. It may be a fantasy of princesses and dragons or it may be the tale of an Auschwitz survivor, but a good poem believes it is real. And it has something vitally important to share, and the words it uses were the most effective ones it could find to say that one thing.

And what doesn't (always) make a poem, and often breaks it?
Metaphors.
Being vague.
Stylistic tenses.
Bad grammar.
Not using capitals.

The list is long, and as with every poem, there are exceptions ;)