Those who surf the internet, buy things online or communicate with friends leave a trail of data. That could become a problem especially for users who have accounts with various services.
"Data collectors can always create a profile from surfing traces," says Martin Mink from the Centre for Advanced Security Research Darmstadt (CASED) in Germany. "But the person cannot be identified until they have an e-mail address, for example from a website."
The European Commission would like to better protect personal data, and presented corresponding reform proposals on January 25. One of the proposals is that website operators should receive the explicit consent of internet users if they want to use their data.
Surfers already have a few tricks to prevent data collection.
Much of the information is sent by the browser. "Websites can review the cache and see which pages have been viewed," Mink said. Those looking to stop that can regularly delete the list of sites visited. The downside is that they have to type in the address manually thereafter. Deactivating cookies also allows surfers to leave fewer traces, but many websites then do not work anymore. That is a typical problem. "You have to find a balance between the protection of your privacy and comfort during surfing," Mink says.
The same happens when logging onto social networks and other web services. Many people prefer to stay logged in all the time rather than having to keep entering their name and password.
While that may be more practical, it also makes it easier for data collectors to connect surfing profiles with personal information such as real names and addresses.
A user profile can also have its advantages, because it allows for search engines and online shops to offer information tailored to the user. Mink nevertheless advises users to be careful. "Profiles with personal data are worth a lot of money. And users have no control over who saves your data and who passes it onto others," the expert said.
Some services and websites allow users to have a least some control over what happens with their data. With the online shop Amazon, for example, users can turn on or off the function of personalised advertisements in account settings. The list of recently visited sites can be deleted here as well. Other online shops also offer similar possibilities.
The corresponding settings are often hidden in interlocking menus, but the search is worth it. Often the pre-set settings allow operators quite a lot of freedoms.
It also makes sense to check the privacy settings in social networks. "Many users put most of their information themselves on the internet," Mink says. Often they are not aware who can access private messages or photos, he explains.
Those who want to know what the search engine operator Google knows about them can visit the site www.google.com/dashboard. There owners of a Google account can see what is saved in which service. Google announced in its blog on Tuesday that user data from Maps, Mail and Docs will be put together in the future.