It's unclear how much of an effect the new policies will have. One consumer group said the changes don't go far enough, and that extensive profiles of people still will be collected without their complete consent.
The new guidelines, which were due to be unveiled Thursday, represent the industry's attempt at self-regulation as Congress and the Federal Trade Commission have been examining online behavioural advertising.
Companies can track consumers as they visit different Web sites, conduct searches and buy things.
Over time, profiles of consumer interests can be sold to advertisers who want to pitch their products only to people most likely to be interested in them. The information collected can include a best guess at someone's ethnicity, income, educational level, age and hobbies.
