A new study shows that less than 20% of parents supervise their children's online activity.
More than 900 parents were surveyed by the National Anti-Bullying Research and Resource Centre, based at Dublin City University.
It found that up to 80% of parents relied solely on what their children told them about which social networks or websites they use.
It also reveals a lack of knowledge among parents about privacy settings like filtering and password controls.
More than half of parents said they use Facebook every day, but far fewer used networks like Twitter and Instagram.
As these platforms have a younger age profile, it makes them harder for parents to monitor their children's accounts.
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