For example, to:</p> <ul> <li>allow ba.com to serve up different versions of a page for marketing purposes </li> <li>control invitations on ba.com for instant credit card offers </li> <li>allow third parties to display appropriate advertising and to track its effectiveness </li> <li>display messages which offer a selection of products based on what you're viewing on ba.com, which are presented to you by our agency when you visit other selected websites.