WHAT IS FRACKING:
* Creation and enhancement of fractures in rock using a gas or fluid injected at high pressure.
* Increases the ability of water and gas to flow through a coal seam, enhancing extraction of gas.
* Accesses gas deposits that can't be recovered using conventional techniques.
* Controversial mining process with exploration companies believing it can be employed safely.
* Opposition from environmental and indigenous groups because of potential for subsurface and groundwater contamination.
* Concerns it can also lead to increased seismic activity, though any events are usually small.
Source: Australian Government. Department of the Environment.