No sooner have you purchased a new pair of shoes online than you’re suddenly seeing them everywhere — primarily in banner ads across other sites gracing your computer screen.

Are you being tracked? In a word: yes. But there are steps you can take to cover your internet tracks.

The fact of the matter is that there are entire lockers of data being gathered online by advertising agencies, from just about every web surfer, whether they consent or not.

This data tracking is a tool for creating a profile of a customer.

The more these ad agencies know about potential customers, the more effectively they can advertise to them.

So long as it remains anonymous, it’s no more than annoying. But as soon as a user is identified, and his movements start getting tracked through the net, it’s no longer a laughing matter.

Blame it on cookies, these internet trackers that hunker down in your computer and make sure you’re always recognisable.

“The advertising networks gather up a user’s surfing behaviour and give him a globally unique identification number,” says Christian Krause of the independent data security centre of the German state of Schleswig Holstein.

“Users with that kind of number on their computer can always be recognised again.” That’s how an online store knows which pages you’ve already looked at and what you did there. But personalised ads are the least of the worries floating out there. Things can get really problematic when you’re on a page where you have to log on with your name, like on a social network such as Facebook or Google+.

“The problem is, that this data gets assigned to your name,” says Thilo Weichert of the Schleswig Holstein centre.

That’s especially worrisome to privacy advocates, since this name-linked data isn’t just for use by the advertising industry, but also companies that want to know a customer’s background or more about his finances. Government agencies also track this data.

And the demand for more data is only growing, according to a study by Xamit, a consulting agency that specialises in data security. It showed that 29.9 per cent of sites inspected during 2011 used a web statistics service that allowed user tracking. The year before, that figure was only 24.7 per cent.

About three-quarters of those sites examined used a service that did not adhere to data security standards, noted Xamit.

But there are strategies internet users can adopt against attempts to suck up data.

“Users should always try to delete stored cookies and the browser history after every internet session,” says Ragni Serina Zlotos of German computer magazine c’t. “That’s possible with all contemporary browsers. With Firefox, you can even set it so that the cookies are automatically deleted after every session.”

But that strategy only works with normal cookies. Online advertisers have upped the ante, now using flash cookies that, according to data security experts, are saved on the computer, independently of the browser. These have to be deactivated in the settings manager of Flash Player, which can be found in the System Controls.

Firefox users should also consider the add-on Better Privacy, which can delete flash cookies and so-called DOM storage cookies.

The browser add-on Ghostery, available for all browsers, also provides some protection from internet snooping. It shows which tracking services and advertising networks are currently following you, and then blocks them. “This has a real ‘A-ha’ effect for a lot of users,” says Krause.

Ghostery also tries to block the tracking. “But you shouldn’t count on that working. The programme performs differently depending on the browser employed,” according to Krause.

A lot of browsers also come with do-not-track functions.

“You can install the browser settings so that you’re not followed,” says Zlotos. Whether internet trackers adhere to those rules is the question. So far, Twitter has required them to honour it.

Another tip: if you’re going to do a lot of surfing with Facebook or Google+, but don’t want to be recognised everywhere, use two browsers, says Krause.

“You use the one for social networks, the other for all other internet sites.” The little bit of comfort you sacrifice is made up for by the protection it provides for your personal data.

Keywords: online dataFirefox