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The General Data Protection Regulation (GDPR) and the ePrivacy Directive (ePR) affect how you as a website owner may use cookies and online tracking of visitors from the EU.


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Cookies are small text files that are stored automatically on your browser by a website during your visit.

But what are they doing there?

Are they harmful or helpful, should they be deleted and blocked, or embraced?

This is an introduction to cookies on the internet. In this article, we will give you a comprehensive description of cookies, what they are and what they do.

Cookies on the internet - the essential

Cookies, these small bits of text that are dropped on your browser while you are surfing the web, are a source of concern for many users. While others may not even be aware of their existence other than as a mandatory pop-up appearing on all but every website, pleading you to “accept cookies”.

What are they and why are they even there?

Please accept marketing-cookies to watch this video.

Cookies explained in 2,5 min. by The Guardian

Originally, the cookie was developed as a service to give memory to the websites, thereby enhancing the user experience and making the interaction between website and user more seamless and intuitive.

While this is still the case, the strong potential of customization and personalization intrinsic to the cookie is a double-edged sword.

On the one hand, the cookie does make your digital life a lot easier.

It customizes your browsing experience, making it possible for your favourite website to welcome you back and, like a friendly waiter, remember your preferences from visit to visit.

Thanks to the cookie, the website presents itself at its best to you as a specific user, providing suggestions and inspiration that match your interests and needs.

Also, the cookie saves you a lot of time and effort, storing your data, so that you don’t have to fill in all of your information on every purchase.

On the other hand, the cookie gathers information about you and your digital activity in a way, that can seem all but clean and transparent.

Using cookies, the website can track your exact actions while surfing: what articles do you scroll past, which ones make you stop and read, what makes you click and share?

Data about users is fast becoming an extremely valuable asset and the methods for gathering them are increasingly sophisticated.

The more firms know about users, the better they can target them and ultimately sell products and maximize profit.

By combining user data such as age, gender and location with a track record of your digital activity, search engines and websites can circle in the users and segment them with an ever-increasing precision.

This subtle segmentation of the users influences all aspects of your browsing experience, from what advertisements that are shown to you, right down to your actual search results.

- Ultimately representing a fundamental democratic issue in regard to the common knowledge and dialogue that is shared in a society.

Definition: What is a cookie and what does it do?

A cookie is a small bit of text which is automatically stored on your computer by a website while you are browsing the site.

The purpose is for the website to be able to recognize you and retain specific information about you. This information might be your login, your language preferences etc., so that you don’t have to start over on every single visit.

In many cases, the sites are customised by cookies, making them indispensable for the website to function properly.

For example, the authentication cookie enables the website to know whether you are logged in on the site or not - and which account you are logged in with - and therefore what parts of the site you have access to.

Being basically a string of text, the cookie can essentially contain anything and serve a vast range of different kinds of purposes.

One might distinguish between the following:

Whereas the first three categories are necessary or serve to optimise the user experience, the purpose of the latter are potentially more controversial.

The vast majority of the cookies installed on your computer during a surfing session belong to third parties and serve to identify you as a consumer, subsequently enabling for a sophisticated targeted marketing to take place on your continued surf through the web.

Cookie checker: What cookies do I have on my computer?

On average, a website stores about 20 cookies on your computer.

All cookies have an expiration date. However, this date may be set far off into the future.

For example, Google AdWords permits for a cookie lifetime of 540 days.  

So if you never block or manually delete cookies, there probably are a quite a few cookies stored on your computer.

This is not necessarily an issue: cookies take up very little space and work in the background.

You may check, edit and delete the cookies on your computer.

However, before checking the “delete all cookies” box, it is worth keeping in mind that you probably will have to re-enter all of your information on your next visit to the various websites.

And also, that new cookies will be installed all over again upon your next visit.

Cookies are stored in the various browsers, so the method for checking your cookies depends on which browser you are using.

To see your cookies, follow the guidelines for your browser in this overview.

How long does a cookie last?

Each cookie has a name and an expiration date.

When a website sends a cookie, it asks your browser to keep that particular cookie until a certain date and time, as written in the text file.

By law, cookies should be deleted every 12 months at least, but some are stored for a much longer duration. In Google Adwords, i.e., a cookie may last up to 540 days.

From a textual point of view, there is no limit to how long a cookie may be intended to last, and examples have been registered of cookies that were made to have a lifespan of +7000 years!

What information does a cookie store?

Being basically small files containing text, the content of a cookie is arbitrary.

Each application developer can choose to put any information they wish in a cookie.

That information can e.g. include your username and password, site preferences, or what you might have left in your shopping cart.

Cookies might hold a vast quantity of information on the user such as age group, gender, geographical location, language preferences, search history and the like.

Essentially, each cookie is a small lookup table containing pairs of (key, data) values - for example (firstname, John) (lastname, Smith).

Once the cookie has been read by the code on the server or client computer, data can be retrieved and used to customise the web page appropriately.

You can try and read the content of a cookie yourself by using the Notebook program on your PC.

Where are cookies stored?

Cookies are stored on the computer hard disk, more specifically in your web browser folder, such as Internet Explorer, Firefox, Safari, Chrome, etc.

The browsers on your computer don’t communicate with one another.

This means in practice, that if you browse for tickets for your next holiday in Safari, advertisements for hotels and car rentals won’t show up in Chrome.

To view and manage the cookies on your computer, you have to check separately for every browser in use on your computer.

See Instructions on how to view and manage cookies in the different browsers here.

What are the different kinds of cookies?

On the overall, cookies can be placed in one of the following categories, based on their duration and on their origin:

How secure are cookies?

From a purely technical point of view, cookies do not represent any threat to your data or computer.

They are neither programs nor spyware.

They are small, passive text files, and can as such not of themselves do anything.

However, cookies hold sensible information, and they do enable third parties to keep track of your digital actions.

With the implementation of the new EU-law on personal data, The General Data Protection Regulation (GDPR), it will become easier for the user to understand what information is being released, to whom, and for what purpose.

But for the time being, the transparency on how the information gathered from the cookies is being used and shared with third parties is, mildly put, limited.

Should I delete cookies?

Cookies operate in the background, so they're not likely to cause much obvious trouble.

However, there are some instances where you should delete them.

The stored data in cookies can sometimes conflict with the website they refer to, if the page has been updated, resulting in errors when you attempt to load the page again.

Also, since cookies are actually files on your hard drive, they do end up taking up some space on your computer.

Although each file is only a few KB in size, they can conceivably add up if left untouched for long enough.

Lastly, cookies are storing your user data and enabling for servers to track your activity.

To secure your privacy, it is thus a good idea to keep a critical eye on what cookies get stored on your computer.

Are computer cookies bad?

From a technical point of view, cookies are harmless.

They are simple text files that are stored passively, and cannot be used i.e. to view data on your hard disk or capture other information from your computer.

However, websites and search engines increasingly use them to track users as they browse the web, collecting highly personal information and often surreptitiously transferring that information to other websites without permission or warning.

Tracking data is also being used to give users and site owners more targeted information or to make recommendations on purchases, content, or services to users.

On the one hand, this is a feature many users appreciate.

For example, one of the most popular features of Amazon.com is the You-Might-Also-like section, which presents targeted recommendations for new merchandise based on your past viewing and purchase history.

At the same time, they can and do gather sensitive personal information and put it to use by e.g. displaying intrusive advertisements targeted to a highly segmented range of users.

Please accept marketing-cookies to watch this video.

See this interesting coverage by The Economist on large scale data brokers, user profiling and targeted advertising. The clip lasts 7,5 minutes and dates from 2014.  

What are cookies, cache and temporary Internet files?

A cookie is a text file created by a website and stored on your computer for future reference.

Cache on the other hand, is a copy of the files or images that you access on the internet.

Each time you access a file through your web browser (Internet Explorer, Firefox, Chrome, etc.), the browser caches (i.e., stores) it.

That way, it doesn't have to keep retrieving the same files or images from the remote web site each time you click Back or Forward.

In some browsers, the cache of the files is stored in Temporary Internet Files.

Temporary Internet files is a folder which serves as the browsers’ storage place to cache pages and other multimedia content from the websites.

You should periodically clear the cache to allow your browser to function more efficiently.

Summing up on Cookies and the Internet

All in all, cookies are one of several instruments in a general pattern, where the Internet is becoming more and more sophisticated as we speak.

This development holds the potential for constantly better browsing experiences.

At the same time, it becomes more and more difficult to understand what is actually going on behind the scenes.

Therefore, a high degree of critical consciousness amongst consumers is increasingly important, as well as an adequate and up to date legislation regarding personal data, data tracking and sharing of data.


Comprehensive introduction to cookies
An article by The Guardian about how DoubleClick and other digital adservices work
An article on Lifewire about how to protect your user privacy on Google
An overview of types of cookies used by Google
A general description of cookies on Lifewire
An introduction to web tracking by The Guardian
A fun introduction to third-party cookies
YouTube video on cookies by The Guardian
Video on YouTube by The Economist about tracking

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