A method and system can be used to identify visitors at a network site (e.g., a website) by using a combination of an address (e.g., IP address) and characteristic(s) of an individual visitor computer. Examples of the characteristic of the individual visitor computer can include the type of the computer, CPU identifier, OS, browser application and version, compatibility of the browser application with other browser applications, display size, screen resolution, locale information, installed plug-in software component(s), mimetypes supported, whether a programming language is enabled, accessory(ies) that can be activated by a browser application, or any other information that may be used in locating or generating a page. The method and system is more accurate than just using an IP address, and the information used for visitor identification will not usually be blocked if cookies are unavailable.