Germans are traditionally keen on protecting their privacy, but the line between personal and public information is blurring and people are left wondering - and often nervous - about exactly who knows what about them.
The private, personal character that makes online social networks appealing to people looking to stay in touch with friends and family is also leading data protection advocates from around the globe to criticize the sites.
Armed with some of Europe's most wide-reaching data protection laws, critics in Germany have accused social networks and other online sites of collecting and making commercial use of personal information without members' explicit permission - as required by law.
Google and Facebook are both under investigation in Germany, as well as other countries, for their privacy and data retention practices.
Deutsche Welle looks at the actions being taken against a number of Web sites and how Germans are using the Web and social media.