Fracking: What is it and how does it work?
A decision has been made to allow fracking to go ahead in Lancashire, in the north-west of England. But what exactly is it?
Hydraulic fracturing, or 'fracking', is a technique used to get a type of gas found deep underground in shale rock.
Shale gas is trapped inside tiny pockets of rock - which makes it hard to reach.
But recent developments in technology have now made it possible to capture shale gas.
How does it work?
Fracking works by drilling straight down and turning the drill horizontally for miles underground.
The aim is to reach the tiny pockets or cracks in the shale rock where gas molecules are locked away.
Water is pumped down to widen these pockets, and the gas is then released and brought up to the surface.
What are the benefits?
The way the UK currently generates energy can't carry on forever, so new methods are needed.
Energy companies say fracking would help give the UK a major source of fuel for the future.
Currently most of our gas is imported from other countries - and that is expensive.
Fracking in the US and Canada has resulted in finding enough gas to last about 100 years.
It's thought that generating electricity from shale gas produces about half the carbon dioxide emissions compared to coal power.
Why are people against it?
Some people are worried about fracking because they think it's too dangerous.
Water companies have warned that drinking water could be contaminated with methane gas and chemicals.
Fracking uses huge amounts of water that must be transported to the fracking site, which has an environmental impact.
There is also the concern that fracking can trigger minor earthquakes.
It's thought two small earthquakes of 1.5 and 2.2 magnitude in the Blackpool area in 2011 were caused by fracking - but this hasn't been proven.
Campaigners think money should be invested in renewable sources of energy, such as wind power.
What does the government think?
A review done by experts for the government in June 2012 found that the risks from fracking could be managed as long as it was done properly.
Any company that wants to begin fracking must apply for a licence before they can do so.