Monday 22 March 2010

Why tracking cookies are bad

What is so bad about a tracking cookie? At the end of the day it doesn't do much it just is a small text file that sits on your computer.

Also a cookie can only be used by one website, so a cookie set on google.com can't be read or used on msn.com.

However if you went on a site called first.com which had a advert shown in a iframe or similar technology which pointed to the domain tracking.com and then you went to the site second.com which also had the same advert on it. The cookie would be able to track you across both sites thanks to the advert. Of course it doesn't have to just be an advert this could be a piece of software specifically designed to track the websites visitors surfing habits.

Many companies and others would like this organisation and I have seen posts about how it is possible to read browsers history to see what websites a user has previously visited.

Thankfully no browser (I know of) allows you to read the users browsing history. However it is possible to get the page you came from by using something like:

echo $_SERVER['HTTP REFERRER']

This is a bit of PHP that gets the page you came from. You can stop your browser giving this information and I will tell you how in another post!

But why would a company want to know your previous surfing habits, well the most common reason would be to sell to you. By seeing what you are interested in and trying to focus their business on the common trends.

Which is fair enough right? After all most major supermarkets do this with their loyalty card you get the card and get special deals and points in return, they track what you usually buy which allows them to focus their business more on their customers. So what is the difference with tracking cookies? Well the difference with loyalty cards is it is in the terms and conditions so you get to decide if you want to partake in the scheme, you get no such choice with tracking cookies which is why it is spying.

Finally I would just like to say not all cookies are bad there are genuine reasons for using them such as providing security and more.

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