Verse is not synonymous with poetry, a poem or lyrics, nor is prose synonymous with narrative, a story or prosaicness. Verse and prose are clearly defined notions, while all of the others are vague. Verse and prose are opposite and mutually exclusive, therefore no in-between forms exist. However, in-between forms do exist between poetry and narrative. Thus free verse is verse and not an in-between form between verse and prose, whereas a prose poem and rhythmic prose are prose. Verse is not obligatory for a poem and poetry, poetry can also be written in prose (the prose poem). Verse is not merely limited to poetry, it can also be encountered in narrative (e.g., a novel or a short short story in verse). Rhythm is optional for verse, some poems in free verse are rhythmless. Poetics (metaphors, symbols and similar) is neither a necessary nor a sufficient condition for verse. Verse, rhythm and poetics are only inherent in typical poems, not in all poems.