Pretty much everyone knows about Rap’s roots in poetry (as, to some, it’s an acronym for Rhythm And Poetry), but I think it’s important to know the differences in poetry and rap music. If one has only been minimally exposed to poetry they wouldn’t really know the difference between a more poetic rapper and one who’s hardly poetic.
Poetry isn’t as simple as rhyming and metaphors, there’s a lot that goes into it. In fact, in recent times (aside from new formalism), poetry is mostly written in “free verse” which is non-rhyming. There are a lot of details concerning these poetic movements though, as New Formalism could very well be inspired by less profound poets like Robert Frost (in comparison to legends like T.S. Eliot). There are a lot of techniques associated with poetry that are often overlooked in rap like meter, structure, consonance, etc. I could write a book on what poetry is and has been for the past few centuries, but that’s not the point of this.
When you study poetry and understand it you get a new outlook and enlightenment to hip-hop lyrics I feel. You start appreciating artists like Aesop Rock more, and sort of feel opposed to the fact that “Poetic Justice” (by Kendrick Lamar) is called “poetic” when it hardly is. I encourage anyway who pays any serious attention to hip-hop lyrics to check out some poetry. You can find a lot of stuff on poets.org
I’d suggest checking out authors like Shakespeare, Edmund Spenser, John Donne, Williams Wordsworth, Rainer Maria Rilke, William Butler Yeats, Ezra Pound, Langston Hughes. Just to name a few.