See elaborations about CPO's in our Best Practices section . People must be able to prevent the collection of their personal data. If they consent to use of their data, they should be able to bar the use of it for other than the original purpose. For example, they might store your passwords and user IDs. They are also used to store your preferences for content or personalized pages.
Most shopping carts use cookies.
These allow you to choose items and leave the virtual store, then return later and find that all the items are still in your shopping cart. Cookies are also used to build a profile of which sites you visit and which banner ads you click on. Advertisers use this information to deliver targeted ads directly to your computer. Some sites save your preferences on the cookie itself. Other sites assign users ID numbers or encoded passwords and keep records of your preferences at their end.