Freestyle rap commonly refers to rap lyrics which are improvised through acapella or with instrumental beats, i.e. performed with few or no previously composed lyrics, off the top of the head. It is similar to other improvisational music such as jazz - Myka 9 of Freestyle Fellowship describes it as being "like a jazz solo" where there is a lead saxophonist acting as the improviser and the rest of the band providing the beat. Rap battles are sometimes improvised in this way.
Originally, in Old School Hip-Hop, the term ‘freestyle’ referred to a pre-written rap verse that was not on any particular subject matter and was just written for the purpose of demonstrating skill. The term is still occasionally used in this way, though the majority of today’s artists use it to mean improvised rapping.
In the book How to Rap, Big Daddy Kane and Myka 9 of Freestyle Fellowship note that originally a freestyle was a written rap on no particular subject – Big Daddy Kane says, “in the ’80s when we said we wrote a freestyle rap, that meant that it was a rhyme that you wrote that was free of style… it’s basically a rhyme just bragging about yourself.”. Myka 9 of Freestyle Fellowship adds “back in the day freestyle was bust[ing] a rhyme about any random thing, and it was a written rhyme or something memorized”. Divine Styler says: “in the school I come from, freestyling was a non-conceptual written rhyme… and now they call freestyling off the top of the head, so the era I come from it’s a lot different”. Kool Moe Dee also refers to this earlier definition in his book, There's A God On The Mic:
"There are two types of freestyle. There’s an old-school freestyle that’s basically rhymes that you’ve written that may not have anything to do with any subject or that goes all over the place. Then there’s freestyle where you come off the top of the head."
In old school hip-hop, Kool Moe Dee says that improvisational rapping was instead called “coming off the top of the head”, and Big Daddy Kane says, "off-the-top-of-the-head [rapping], we just called that “off the dome” — when you don’t write it and [you] say whatever comes to mind”.
Referring to this earlier definition (a written rhyme on non-specific subject matter) Big Daddy Kane says, "that’s really what a freestyle is” and Kool Moe Dee refers to it as “true” freestyle, and “the real old-school freestyle”. Kool Moe Dee suggests that Kool G Rap’s track ‘Men At Work’ is an “excellent example” of “true” freestyle, along with Rakim’s ‘Lyrics Of Fury’.
Since the early ‘90s onwards, with the popularization of improvisational rapping from groups/artists such as Freestyle Fellowship through to Eminem’s 8 Mile, ‘freestyle’ has come to be the widely used term for rap lyrics which are improvised on the spot. This type of freestyle is the focus of Kevin Fitzgerald’s documentary, Freestyle: The Art of Rhyme, where the term is used throughout by numerous artists to mean improvisational rapping.
Kool Moe Dee suggests the change in how the term is used happened somewhere in the mid to late ‘80s, saying, “until 1986, all freestyles were written”, and “before the ‘90s it was about how hard you could come with a written rhyme with no particular subject matter and no real purpose other than showing your lyrical prowess”.
Myka 9 of Freestyle Fellowship explains that Freestyle Fellowship helped redefine the term – “that’s what they say I helped do - I helped get the world to freestyle, me and the Freestyle Fellowship, by inventing the Freestyle Fellowship and by redefining what freestyle is… We have redefined what freestyle is by saying that it’s improvisational rap like a jazz solo”.
"A lot of the old-school artists didn’t even respect what’s being called freestyle now... any emcee coming off the top of the head wasn’t really respected. The sentiment was emcees only did that if they couldn’t write. The coming off the top of the head rhymer had a built-in excuse to not be critiqued as hard".
A number of rappers learned to rap through improvised freestyling and by making freestyling into a rhyming game which they played often - as described by artists such as MC Shan, David Banner, and One Be Lo in the book How to Rap. In the same book, reasons for freestyling given by K-Os, Bobby Creekwater, Cappadonna, El Da Sensei, and Myka 9 include - for entertainment, as a therapeutic activity, to discover different ways of rapping, promoting yourself, being versatile, and as a spiritual activity. Improvised freestyling is also a skill that can be used in live performance, to do things such as giving something extra to the crowd and to cover up mistakes. Artists will often refer to places and objects in their immediate setting.
Improvised freestyling is also a way of recording songs for albums or mixtapes, as described by Myka 9 and Cashis - other artists such as DJ Quik, T3 of Slum Village, Evidence of Dilated Peoples, Myka 9, Mr Lif, and Zion I discuss the pros and cons of this in How to Rap and how it can help them come up with ideas.
Freestyles are either performed a cappella, over beatboxing (as seen in Freestyle as Black Thought improvises over Questlove's beatboxing), or over instrumental versions of recorded Hip-Hop songs. Often, freestyling is done in a group setting (called a cypher) or as part of a freestyle battle. In these cases, freestyle verses are often prepared in the rapper's head as the other rappers in the cypher or the opponent in the battle take their turn. Metaphors and similes are often used when freestyling and a good punch line is huge when freestyling in a cypher.
Due to the improvised nature of freestyle, rules for meter and rhythm are usually more relaxed than in conventional rap. Many artists base their set on the situation and mental state, but have a ready supply of prepared lyrics and rhyme patterns they can use as filler or even around which they can build their set.