What are Cookies?

What are Cookies? How do they work?

In general, a cookie is nothing to be afraid of. It’s a tiny piece of information, mostly a text file, deposited unsolicitedly by websites on the visitor’s computer. If the user returns to the site, it can extract the data from the cookie. The duration of the storage is limited, which is also recorded in the cookie, along with the website’s name or path and respective additional information.

What are they used for? Do users benefit from them?

The HTTP connection between user and server is stateless and is not able to allocate certain page impressions to a certain user. With cookies however, it is possible. A cookie can memorize a session ID which is then able to identify users when clicking through sub pages. This is for example applied for virtual online shopping carts. If the user reserves a product, this information will be allocated to his session ID. If he then continues to browse the shop, all other reserved products can be allocated to his session ID as well.

Cookies are also used for caching. In order for already entered user data not to get lost in unexpected disconnections, they can be saved temporarily with the help of cookies. If the connection is up again, the server is able to extract previously entered data from the cookie. As the stored content is random, the server can also record user behaviour on the website without him noticing it and create individual surfing profiles. This can then be allocated to the respective customer, which allows online shops to send targeted advertising mails. In other words – a surfing profile can be explicitly matched with the respective user. It is also possible to set third party cookies via e.g. ad banners. With such tracking cookies, it is also possible to identify users on different websites. The surfing profile can then be created across servers, in order to display personalized websites for users.

What can users do?

Every user can decide on his own whether he likes cookies and wants to accept them. Cookies can be enabled, blocked and also deleted in the browser settings. The standard settings differ from each other – one needs to either accept or deny the usage of cookies. These settings are possible because it’s actually the browser that stores the cookies. A website or server is not entitled to store data locally with the user, which is why they ask the browser to do it for them instead. If the user doesn’t agree to the settings, the browser won’t store anything. The respective settings can also be changed during an on-going session without having to restart the browser.

When should cookies be deleted?

When speaking of public internet access points and anywhere where people are using the same computer, one should always think of deleting cookies. If cookies remain stored, subsequent users can continue the very own session – which is why cookies should be deleted by all means in such situations.

Note: the original article is in German written by Irina Hey – “Was sind Cookies”. Translated by Johanna Wollenweber.