Matching between advertisement and target consumer is achieved in a system which maintains consumer privacy. Such system includes computer end users, an advertising service provider and advertisers. Computer end users subscribe to the advertising service provider. The advertising service provider sells time or other accountable units to the advertisers. The advertiser provides the advertisement. Each advertisement has accompanying demographic information or a desired affinity ranking. The end user completes a demographic questionnaire and ranks various categories of products and services. The advertising service provider sends executable filter programs which run on the end user computer to test whether a corresponding advertisement is to be downloaded and displayed. Alternatively, the user sends out a request for advertisements to the advertising service provider, and the advertising service provider finds advertisements meeting the target demographics requested by the end user or which comply with the affinity rankings.