Is rap music singing or is it overlaying lyrical content with a musical background!?

depends when.. in a song. some choruses have singing and rapping. pharcyde, deltron 3030, and in this one song called "the weed song" by bone thugs it was more of a singing song that mixed rap into it. so really it depends what type of rapppers/rap groups they are. 2day tho its overlaying lyrical content with a musical background.