Fracking, or hydraulic fracturing, is one of several unconventional techniques for extracting gas from underground rock formations. A different technique can be used to extract coal bed methane (CBM). A third technique is called underground coal gasification. The techniques are all fairly new to the UK, although they have been used elsewhere in the world for many years.
So far only exploratory work has been carried out in the UK to find out about shale gas availability. However, two CBM projects in Scotland are nearing the production stage.
The UK Government considers shale gas to be a national priority. It regards it as having the potential to make the country less dependent on imported energy, and to help promote growth and provide jobs.
But there is strong opposition from local communities in some areas. They fear the procedures are unsafe and could result in water contamination, air pollution, earth tremors and other harmful effects.
Others object because of the greenhouse gas emissions and their contribution to climate change. There is also concern that fracking may push down the price of gas, making it uneconomical to develop low-carbon renewable technologies.
The Scottish Government takes a cautious, neutral approach, and has declared a moratorium on all three techniques while further research and public consultation is undertaken.