Safer Internet Day is being marked around Europe with events to educate children and parents about net dangers.
Schools are being encouraged to discuss net dangers
Themed events will reveal the risks of sharing too much personal data and warn children that their virtual friends may not be who they say they are.
Public events will encourage parents to oversee their children's online life so they know who they are talking to.
In the UK schools were encouraged to run assemblies that discuss how children should behave online.
This is the fifth Safer Internet Day and this year more than 50 countries are expected to take part.
Prior to the day schools, youth groups and clubs were encouraged to undertake projects that get children thinking about what they do online and how to stay safe while they do.
Those taking part were asked to produce publicity materials, such as leaflets, posters and videos, which warn children about the dangers or emphasise safe net use. Cash prizes are on offer for those judged to have produced the best materials.
Local authorities have also been running events to help educate parents.
A spokeswoman for the Child Exploitation and Online Protection, which is co-ordinating the UK's involvement, said its efforts were being focused on getting schools to run assemblies that discuss the issue.
Teaching materials for both younger and older children had been produced to help teachers prepare.
Buttons to help children report problems are being used online
"It's about getting them talking about the issue, the personal information they put online and their social networking profiles," she said.
A short film has been produced for older children that spells out the potential dangers for teenagers of meeting the people they get talking to online.
One of the most important points for children to realise, said the spokeswoman, was that the people they talk to might not be other youngsters.
"If they are going to meet someone in the real world they should make sure to take a trusted older person or an adult," she said.
"The message is getting through," she said, "and now it's about refining that message."
In a global survey conducted by security firm Symantec, it was found that 75% of parents did not know what their children are doing online.
In the UK, adults believed that 4% of children had been approached by a stranger. The actual percentage was 20, the survey found.
UK organisations are banding together to create the Information Security Awareness Forum (ISAF) that will co-ordinate the broad array of work being done to educate consumers and companies about online security.
"There are a lot of messages coming out from lots of different places but the question is who do you listen to?" said Dr David King, chair of the ISAF.
The organisation is planning to produce best practice guides for businesses and to run events that raise awareness about computer security.
"It's about our work overlapping rather than duplicating," said Tony Neate, head of Get Safe Online which has signed up to ISAF.
He said although more people were starting to use anti-virus, firewalls and anti-spyware programs, protection meant more than just installing software.
People also needed to be aware of the "social engineering" threats in which con artists use technology to make their scams more plausible.
"This is everyone's responsibility," he said.