This is a poem that uses ten syllable lines in stanzas of four usually. A form of poetry that is similar to this is a sonnet. Sonnets have a specific rhyme pattern, though. A Shakespearean Sonnet is a structured poem consisting of fourteen lines arranged in three quatrains that are four-line stanzas, ending with a rhyming couplet. Each line of the sonnet is composed in iambic pentameter.
Free verse is a poem that has no form.
There is not a specific number of syllables or any rhyme. These poems almost appear at a first glance like short pieces of prose. What sets them off from prose is the use of intense imagery and description. Free verse is also on one very specific theme, which is one definite way to know that it is poetry. Some authors use punctuation when writing poetry and others do not.