Please give a suitable definition of poetry that may cover all its areas.
Poetry has a definite purpose and any poem is an interpretation of a person's views or an attempt to express a viewpoint which needs analysis to be fully understood. It is highly symbolic and often difficult to assess. This helps to serve its purpose as being interpretive and allows the reader to deduce his or her own meaning whilst still being mindful of the poet's likely intention.
Poetry is expressive and emotional and brings seemingly different people together in terms of common experiences, although the way they experience them may be quite diverse. Expressing a viewpoint in a poem is perhaps somewhat less confrontational than letter-writing and more subtle in its rhyme schemes or rhythm.
Poetry places emphasis on things that may otherwise be overlooked and brings real meaning to the word "appreciation." This does not infer that a person must enjoy the poetry, just understand and appreciate the poet's own style. Poetry is a way of attaching meaning to the seemingly mundane or adding beauty to an ordinarily awful subject. It allows the poet to discuss issues that are too delicate, embarrassing, fickle, unimportant, shocking or just plain terrible to contemplate in the normal scheme of things; similarly things that cannot be explained in the normal course.
When poetry was popularized, poets used recognized poetic forms to ensure readers could remember their poetry and so that they were taken seriously after which they could adapt their own style. To ensure a readership, poets needed to use expressive language that would be remembered and retained by the reader for later clarification and discussion.
Poetry allows for the use of imagery and figurative language that may otherwise escape the reader. The strong images lessen the need for a long, drawn-out narrative. Whilst it is often seem as complex, poetry attempts to present a simplistic, or at least, unfettered, version of a circumstance, event and so on.