PopUpCop is designed to return control of your browsing experience back to you. It does not block all advertisements: it blocks irritating Web site behavior, which is often used for advertisements. Like the ideal of a real police officer, it steps into a volatile situation and uses just enough force to restore calm. Because there are millions of very different people using the Web, and because each may have a different irritation threshold, PopUpCop is completely customizable. A PopUpCop user can choose what techniques and technologies to block, from blocking nothing to turning off images, Java applets, ActiveX controls, JavaScript, and 15 other potentially annoying techniques. Users also may want to change what to block depending on where they are browsing. To make all this flexibility easy to control, PopUpCop features two key control mechanisms: the Internet irritation indicator and the Internet irritation level slider. These two controls work together to provide information about the techniques that a web site is using and to make it easy for the user to block a collection of techniques. Unlike some of its competitors, PopUpCop does not use site title or URL address matching when determining what to block. It monitors your interaction with the browser, and determines what new windows to block based on a simple collection of rules. It never interferes with normal browsing and will never close the main browser window. If you just want to block popups, you can just install the program and forget it. PopUpCop is packaged as an Internet Explorer toolbar add-in. After installation, it occupies a small space on the user's toolbar. It safely co-exists with other toolbar add-ins, like the Google toolbar.