RHI scheme - what was it?published at 09:40 British Summer Time 2 October 2018
The Renewable Heat Incentive scheme - or RHI for short - came to the fore of the Northern Ireland public's knowledge in late 2016.
The fallout from the scandal attached to it is still being felt in the region's politics today.
The scheme was set up by the Northern Ireland Executive in 2012 as a way of encouraging businesses to switch from using fossil fuels to renewable sources for generating their heat.
Those who signed up were offered financial incentives to buy new heating systems and the fuel to run them.