What is a cookie?

What is a cookie?

We're well into the holiday season, and what would the holidays be like without cookies. Buckeyes, chocolate chip, and of course Facebook tracking cookies. Not familiar with the last one? Well, it's very familiar with you. In fact, if you've logged into Facebook on your phone, your work PC, or anywhere else it knows almost every website you're been.

Sounds scary? It shouldn't be, cookies are everywhere and when used properly can be safe and useful. In essence, they are a small piece of data contained in your web browser that help to retain information that the website needs - like the name you put into a name field, what's in your shopping cart, or if you liked or shared that news article. Cookies are anything but private but they serve important functions and you're connected to the largest store of information ever in human history (the internet) which makes being completely "untrackable" difficult and you soon wouldn't be able to function normally without cookies which do much more than track your presence.


Just like their namesake, cookies come in different flavors and with different uses. The most common flavors are session and persistent cookies. Session cookies are pieces of information that hold data for as long as you have the browser window open - shopping carts are an example of this type. They hold temporary data to allow websites to function but carry no expiration date and this tells browsers to destroy them every time the window is closed. Persistent cookies are pieces of data which are time stamped with an expiration date and these cookies exist until however long or short the creator wants. They are generally used to keep you logged into that portal you always use at work or help to make sure you don’t have to remember your password every time you log into your web mail. These cookies sometimes have the job to tell the creator when a user views or clicks on a piece of a website that exists on another website (for example a Facebook Like button or an advertisement for Amazon on a news site) and are sometimes called tracking cookies. But flavor doesn't qualify the use of the cookies and session cookies can be used to track and persistent cookies can be used for shopping carts as well. It all depends on the website creator and what function he wants his or her cookie to accomplish.


There a three main uses for cookies: logon management, personalization, and tracking. Logon management is what records what is in your shopping cart and carry's unique identifiers to know that it's you when logging into your Gmail - giving you your mailbox and not other users. Personalization cookies assist in customizing the webpage for the user - webpages that let you adjust the color or the size of the text and then hold that information for your next session are personalization cookies. The most prevalent and possibly nefarious are tracking cookies. When you visit a website for the first time, if the website knows it's your first time they will send you a unique identifier that is tied to your IP address (basically your address on the internet). Anytime you requests anything for that website or from another website that contains a part of their website (Facebook.com or any Facebook like button that you see) it stores the website URL or address (ex. www.google.com), the date/time you visited the page, and what cookie you're using in a log file that is transmitted to the cookie's owner. Well, what does that matter?


Nothing you do on the internet is a secret first of all. If you really don't want people to know what you do, being connected to a giant information machine is not the way to do it.

Second, Facebook offers you a free service. The way they pay for that is through providing marketers a way to target advertise to people in very narrowly focused groups. This goes for Google as well. So letting Facebook and Google get to know you better so they can clump you in the right advertising group is the 'price' of using their free services.

Other than trying to get you to spend all of your money, what insidious plans do you think they have for all that data? According to those in large marketing data aggregation that at some point you are no longer Bob at 123 Oak st that likes watching cat videos and inspector space time fan fiction. You are just a number, and even then a fraction of a fraction of a percent. Picking you out as a single person from the thousands of other people that fit your exact same activity profile just holds zero value to anyone.

What can / should you do?

If you're really worried about cookies, you could shut off cookies completely but you'll soon find that the internet doesn't work as you want it to. You'll sign out of Facebook the moment you log in, nothing will stay in your shopping cart, and certain websites might even cease to function. What you could do, is check and modify your ad preferences. Google and Facebook make their ad policy transparent for their users and opting out of these programs severally reduces their tracking of your cookies. Even if you don't want to opt out, it's interesting to see what Facebook and Google think you are interested in - and to see how right/wrong they are. See below for the links to Google and Facebook respective ad preference pages.



Written by: Michael Perry, Network Engineer