How Do Websites Use Cookie Technology

How Do Websites Use Cookie Technology?

A cookie allows a website to store "state" information on your computer. This information allows for a website to remember what "state" your browser is in. An ID is one simple piece of state information. If an ID exists on your computer, the website knows that you have visited before. The "state" is - Your browser has visited the website at least one time and the website knows your ID from that visit.

Websites use cookies in different ways, here are some common examples:

  • Websites can accurately determine how many people actually visit the site. It turns out the only way for a website to accurately count visitors is to set a cookie with a unique ID for each visitor. Using cookies, sites can determine:
  • How many visitors
  • New visitors vs. repeat visitors
  • How often a visitor has viewed the website
  • Websites use a data base. The first time a visitor arrives, the website creates a new ID in the database and sends the ID as a cookie to the visitor's computer to be stored. The next time the user comes back, the website can increment a counter associated with that ID in the database and know how many times that visitor has been there.

  • Websites can also store user preferences so that the site can look different for each visitor. For example, if you visit, it offers you the ability to change the content/layout/color of the homepage. It also allows you to enter your zip code and get customized weather information.

  • E-commerce websites can implement things such as shopping carts and checkout options. The cookie contains an ID and lets the website keep track of you as you add items into your cart. Each item you add is stored in the site's database along with your ID. When you check out, the site knows what is in your cart by retrieving all of your selections from the database. It would be impossible to implement a shopping mechanism without cookie technology.
With these examples, note that all the website's database is able to store are the things you have selected from the website, a log of the pages you have viewed on the website, and information you have provided to the website. All of the information is stored in the website's database, and in most cases, a cookie containing your unique ID is all that is stored on your computer.

How Do Websites Use Cookie Technology - Introduction To How A Internet Cookie Works

Introduction To How A Internet Cookie Works

Most Internet cookies are simple devices that have taken on a life of their own. Cookies began receiving attention in 2000 because of Internet privacy concerns.

A cookie provides capabilities that make the World Wide Web much easier to navigate. The designers of major websites use cookies because they provide for a better user experience and make it easier to gather accurate information about you the visitor.

On this blog, we explain the basic technology of cookies and some of the features they provide.

How Do Websites Use Cookie Technology - How The Internet Cookie Works

How The Internet Cookie Works

Cookie data is name-value pairs stored on your hard-drive by a website. The website stores data on your computer and retrieves it when you return to the site to remember who you are. A website can only retrieve the data it has stored, and is not able to look at another cookie stored or other data on your computer.

The data moves in the following manner:

  • When you type the URL of a website, your browser sends a request to the website for the page. For example, you type to your browser and your browser then contacts Ebay's server and request its home page.

  • When the browser does this, it will look on your computer for a cookie file that Ebay has set with a previous visit. If it finds a Ebay cookie file, your browser will send all of the name-value pairs in the file to Ebay's server.

  • Ebay's server receives the cookie data and the request for a page. If name-value pairs are received, Ebay can use them to identify your interests with previous visits.

  • If no name-value pairs are received, Ebay thinks that you are a new visitor. The server creates a new ID for you in Ebay's database and then sends name-value pairs to your computer. The process of storing name-value pairs on your computer begins again.

  • The Web server can change name-value pairs or add new pairs whenever you visit the site and request a page.
There are other pieces of information that the server can send with the name-value pair. One of these is an expiration date. Another is a path (so that the site can associate different cookie values with different parts of the site).

You have control over this process. You can set an option in your browser so that the browser informs you every time a site sends name-value pairs to you. You can then accept or deny the values.

How Do Websites Use Cookie Technology - Problems With The Cookie

Problems With The Cookie

A Cookie is not a perfect mechanism, but they do make a lot of things possible that would be otherwise impossible. Here are some reasons why a cookie is imperfect.
  • Computers used in public areas and many computers used in office environments, or at home, are shared by multiple people. You use one of these computers to make a purchase and the online store leaves a cookie on that public computer. It's possible that someone could later try to purchase something from the store using your account. Online stores usually post large warnings about this problem, but mistakes happen. For example, I had once used my girlfriend's computer to purchase something from Amazon. Later, she visited the Amazon site and clicked the "purchase" button again, not realizing that it created a second purchase of a book.

  • A Cookie can get erased - If you have a problem with your browser and call for support, the first thing tech support will ask you to do is to erase all of the temporary Internet files. When you do that, you lose all of your cookie files. Now when you visit a site again, that site will think you are a new user and assign you a new cookie.

  • Multiple machines - People often use more than one computer during the day. For example, I have a machine in the office, a machine at home and a laptop for travel. Any site I visit from these three machines will track me as three separate users. Recording a false number of unique visitors and/or buyers.

How Do Websites Use Cookie Technology - Why All The Huff About The Cookie?

Why All The Huff About The Cookie?

You might be wondering why there has been so much uproar with the media about cookie technology and privacy on the Internet. We have shown that a cookie is a benign text file, and that they provide lots of useful capabilities on the Web.

There are two main things that have caused concern about the cookie:

  • The first has to do with online companies selling your information to other interested parties who want to sell you something. With cookie technology, a website can track not only your purchases, but also the pages that you read, the ads that you click on, the pictures you view, etc. If you purchase an item and enter your name and address, the site potentially knows more about you than a traditional mail order company would. This makes Target Marketing much more precise, and that makes a lot of people uncomfortable.

    Different sites have different policies and most well-known online stores have a strict privacy policy and do not sell or share any personal information about their visitors with any third party, except in cases where the visitor tells the site to do so.

How Do Websites Use Cookie Technology - Why All The Huff About The Cookie? continued

Why All The Huff About The Cookie? continued

The second is unique to the Internet where certain providers can actually create a cookie that is visible on multiple sites. DoubleClick is known for this and many companies use DoubleClick to serve banner type ads on their sites. DoubleClick can place small GIF files on the site that will allow DoubleClick to load a cookie on your machine. DoubleClick can then track your movements as you surf the web. It potentially can see the search words you type into search engines. Because it gathers so much information about you, DoubleClick can form very rich profiles. These are still anonymous, but they are very informative.

DoubleClick then went a step further by acquiring a company and threatening to link these rich anonymous profiles back to name and address information -- it threatened to personalize them, and then sell the data. That began to look like spying to most people, and that is what caused the concern.