What the heck is Fracking?

1. What is the purpose of "fracking?"
2. How is "fracking" done?
3. Why are people concerned about "fracking?"

1. drilling technique; To get natural gas
2. Fracking, in which water and toxic chemicals are injected at high pressure into the ground to break up rocks and release the gas trapped there, occurs thousands of feet belo.
3. their health has been damaged by living near gas-drilling sites. The natural gas has been contaminating people's drinking water.