50% of European teenagers give out personal information on the web – according to an EU study – which can remain online forever and can be seen by anybody. Today, Safer Internet Day, the European Commission is passing a message to teenagers: "Think before you post!" It welcomed actions to protect children using social networking websites taken by the 20 companies who signed the Safer Social Networking Principles last year. Most of these companies have empowered minors to tackle online risks by making it easier to change privacy settings, block users or delete unwanted comments and content. Yet more needs to be done to protect children online, the Commission says. Less than half of social networking companies (40%) make profiles of under-18 users visible only to their friends by default and only one third replied to user reports asking for help.