They are controversial groups. They pose as children on chatrooms in order to expose online groomers.
Some accuse so-called 'paedophile hunters' of being vigilantes while others praise them for keeping children safe.
Paedophile hunter groups are on the rise in the UK, and our current affairs programme Ein Byd(Our World) has been following the work of two of them in Wales as they hunt down online predators.
In a special programme tonight on S4C, ITV Wales’ reporter Siôn Jenkins went to meet the groups 'PH Balance' and 'Welsh Children Protector' to follow them on a sting where they confront potential online predators.
They are just two of the 75 paedophile hunter groups that operate in the UK.
Nick Young started the group PH Balance in April 2017 and since then he and his team have gathered evidence on 18 individuals.
ITV Wales went along to one of PH Balance’s stings - where they confronted a 44-year-old man called Neil Cooper.
He was found to be speaking sexually to two members of the group on chatrooms - or decoys as they’re known. They had been posing as 14-year-old children.
During the conversation with the one of the decoys, called Olivia Jane, Cooper had written “you’re beautiful and sweet, Olivia” and “Olivia I like you...I have come to like you a lot. I would risk it if you really wanted me around.”
After questioning Neil Cooper for his actions the team called the police and placed him under citizen’s arrest. The group handed over their catalogue of evidence to the police and Cooper was taken to the local station.
Following the sting conducted by 'PH Balance' at the hotel in Newport, Neil Cooper was kept on remand in Swansea Prison for two months, having pleaded guilty to inciting a child to engage in sexual activity, and has since appeared in court. He was sentenced to eight months imprisonment - suspended for two years.
The judge also ordered Cooper to carry out a 30-day rehabilitation requirement as part of his sexual harm prevention order. He was placed on the sex offenders register for ten years.
The Police and Crime Commissioner for Gwent Police, Jeff Cuthbert, has said he can see some benefits in the idea of the police co-operating with paedophile hunters.
However, Nick Young from 'PH Balance' had also received a letter from Gwent Police stating they could not support the work of PH Balance:
“We understand your concerns regarding the internet activity of paedophiles... but stress that the activity you propose could lead to you committing offences and should be left to law enforcement. If any offences have been committed by you or any member of the group you will be dealt with.”
In a response to the letter, Gwent Police said:
But Nick Young from 'PH Balance' said he has no plans to stop anytime soon.
“I will prove to them that PH Balance will continue to do what we’re doing and we will continue to bring these individuals to justice”
Who can you contact if you’ve been affected?