How do I delete cookies? And just what are cookies, anyway?

Cookies can be used for many things. The simplest case is remembering who you are. When you visit a site like Amazon.com and log in, Amazon might place a cookie on your machine that contains your account name, and the fact that you're logged in. When you come back a day later Amazon.com picks up the cookie and sees who you are and that you had successfully logged in the day before.

Privacy concerns typically arise from cookies used by embedded advertising or other content on web sites; sometimes called "third party" cookies. Since the ads are typically served up from some other website, they can drop a cookie of their own. Advertisers can then keep track of how often you visit which sites they have their advertising on.

Now before the paranoia kicks in, let's be clear about something - they don't care about you specifically. Sorry, but you're just not that important. The sheer volume of data alone makes tracking any one individual a difficult task. What's typically interesting is aggregate data: the data that says things like X percent of the visitors to this website also visit that website.

That's not to say that cookies can't be misused; it's just that it's typically a lot more work than it's worth.

You can see what cookies you have and what they contain, but it's typically not particularly interesting. In Internet Explorer, hit Tools, Internet Options, the General tab, underneath Temporary Internet Files click on Settings. In the resulting dialog click on View Files. That'll bring up a list of all all temporary files, including cookies. I typically click on the Name column header to sort by name, and then scroll down to the point where the name begins with "Cookie:". There they are.

Another approach is to download a Cookie viewing program to make things a little more readable. I've used Cookie Viewer from KarenWare.

In either case, if you look at the contents of a cookie, they're typically very obscure. It's common practice to simply store a unique identifier of some sort and not much more. That ID usually makes sense only to the website that put it there, and effectively makes the cookie useless to others even if they could get at it.

Deleting cookies is easy. You probably saw the button on the way to viewing them earlier: back in IE, hit Tools, Internet Options, the General tab, and there's a Delete Cookies... button. Click it, answer yes to the confirmation, and the cookies are deleted. And, among other things, you'll now have to login again to every site that had saved your login using a cookie.

You can control how Internet Explorer handles cookies to reduce any concerns you may still have. On the Privacy tab of Internet Options you can set the level of cookie handling IE should follow. That includes not only allowing, or blocking, all cookies, but also controlling third-party cookies resulting from things like embedded ads I mentioned earlier. And you can define an explicit list of sites from which you're prepared to accept cookies.