Has this happened to you? You are using a certain search term in Google, for example ‘tablet’. Shortly after, your screen is filled with an advertisement for a tablet. What a coincidence! Errm… no it isn’t. Because smart online marketing companies are tracking your surfing behaviour. Watching the sites you visit and the search terms you enter. They use that information for targeted internet advertising. How do they do that? By installing cookies on your computer or mobile device.

What are cookies?
A cookie, also known as adware, is a small text file that is installed on your computer or mobile device when you visit a website. A cookie stores information about your website visits and surfing behaviour. The next time you visit, the website will recognize you. That can be useful. But that same website can also pass your surfing information on to data traders and manufacturers.This TED presentation shows how lucrative this kind of data trade is. You can also watch how personal details are used for malicious purposes. Pharmaceutical companies and insurance companies for example, are very interested in medical data. Because that information can be worth a lot of money: by using it for advertising and promotion, but also by excluding people from a policy.

Block cookies with an ad blocker
An ad blocker is a piece of software that blocks internet advertisements. An added advantage is that your mobile device no longer needs to load unwanted pop-ups, so your surfing speed goes up while data usage goes down.

Suitable ad blockers
There are many ad blockers, often available for free, for almost any browser and operating system. Here are a number of good ad blockers:


Try it out
You don’t want to reveal your personal data on the internet? We recommend installing one of the ad blockers above. Just try it out. Attention: some websites do not function fully after they see that you have installed an ad blocker, because they make money from advertising. Depending on the ad blocker, you can always decide to make an exception for such a site. More information about ad blockers? Contact Privacy and Security via privacy-en-security@nhlstenden.com.


DNS filters

Before you approach a site, for example datacare.nhlstenden.com, it must  first be converted to a so-called ip address. DNS (Domain Name System) was invented for this. Unless you enter an IP address directly, a so-called DNS query is always used.

This also offers the possibility to check whether the requested address is correct during this query. Because of this, the chance that your system gets infected when you click on a link in an e-mail is a lot smaller. The best known service that offers this is Opendns.

Please note: all your pages that you consult are now known to opendns instead of your own internet provider.