What are the four pillars of hip pop?

There are five pillars of hip hop, not four. The five pillars are:

1. MCing (also known as rapping): the act of speaking rhythmic lyrics over a beat.

2. DJing: the art of playing music on turntables and mixing different records together.

3. Breakdancing: a form of street dance that combines acrobatics, tumbling, and breakbeats.

4. Graffiti: the art of writing or drawing on walls or other surfaces.

5. Beatboxing: the art of producing vocal percussion sounds using one's mouth, lips, and tongue.