Guidescope: How Cookie Blocking Works

How Cookie Blocking Works

What are Cookies?

Cookies are unique identifiers that Web servers place on your computer when you visit a site, view a graphic, or load an invisible Web bug. (Web servers are Internet computers that send you Web page contents.) Cookies help sites identify you. Many sites use them to tailor their content to you, which can be useful. However, cookies are also used by Web servers to track your surfing behavior, often without your knowledge or consent. Web advertising companies that track your surfing use cookies.

How do Cookies work?

Whenever your browser loads a page or a graphic from a site, that site has a chance to set (or write) a cookie on your computer. It does so in the "header", a hidden part of the conversation between your browser and the server. The next time your browser requests a page or graphic from that server, your browser automatically sends any cookies it has from that server back to it in the header that is part of the request. This allows the server to tailor its contents to you or, if it wants, to track what you view and when.

How do you block Cookies?

Our software blocks cookies by stripping them out of the headers (described above). All cookies are blocked except those from sites to whom you give permission to set and read cookies on your computer. Our Cookie List helps you determine which sites attempt cookie transactions and lets you specify which sites have your permission to do so.

JavaScript and Cookies

Sites can also set cookies on your computer in a JavaScript script that is part of the page sent to your browser. Our software does not block cookies that are set using JavaScript. If you are monitoring cookie activity using your browser, you might see sites that are not allowed in your Cookie List attempting to set cookies. Even if a cookie is set using JavaScript, the cookie will be stripped from the headers when your browser attempts to send it back to the site that set it.

SSL and Cookies

To protect your privacy and maintain security, Guidescope does not block cookies or examine data streams associated with pages of Internet sites that use SSL (Secure Sockets Layer), an option commonly used on order forms that collect personal information such as credit card numbers.

Can't I control cookies using my browser?

Browsers typically provide some limited control over cookies. They usually allow you to:

Disable all cookies:
This provides privacy but prevents access to many sites that you might want to visit that require you to accept cookies.
Accept all cookies:
This provides you with no control over cookies on your computer.
Warn/prompt before accepting cookies:
This sounds good until you try it. If you do, then you will probably be overwhelmed dealing with all the requests to place cookies on your computer.

We found that these browser-provided controls didn't provide enough control to effectively manage cookies. We use the Guidescope cookie controls along with the "warn/prompt before" browser controls. That way, we can monitor the sites that we explicitly allow to place cookies on our computers and aren't bothered by other sites that try to.