Improved techniques for customizing information provided from a content server through a network to a user of a computer system in accordance with demographic classifications, user interests, or preferences are disclosed. Such customizing can involve banner advertising on the Internet whereby the advertising banners are able to be targeted to the user. The customizing can also involve altering portions of a web page to be displayed to the user so that the web page is more effective, useful or desirable for the user. Besides customization of the information to be displayed to the user, the invention also provides techniques for obtaining demographic information about the user of the computer system, and techniques for transmitting the demographic information over the network so that remote content servers that provide information content to the user can do so with knowledge of the demographic information about the user.