There is controversy over where the line should be drawn on the use of this technology. Cookies store unique identifiers on a person's computer that are used to predict what one wants. Many advertisement companies want to use this technology to track what their customers are looking at online. This is known as online behavioral advertising which allows advertisers to keep track of the consumer's website visits to personalize and target advertisements. Evercookies enable advertisers to continue to track a customer regardless of whether their cookies are deleted or not. Some companies are already using this technology but the ethics are still being widely debated.