Its called "street dance" because it originated on city streets in the late 1980's and early 1999's. It was a way for gangs to stop trying to kill each other. :)
"Street dance" in formal dance terminology refers to the dances that evolved in urban areas. Towards the end of the "industrial revolution", the world became urbanized and dance professionals needed...
street dance is a form of hip hop! hip hop is a dance where you can relax the muscles but pop and move parts of your body with out being stiff! It is very unique dance and It orginated from hip hop...
Modern dance consists of dancing to different music such as African. I consider it to be most like jazz in how your body moves and what muscles are being used; however, it doesn't use the same moves....