Online shoppers let slip plenty of information about themselves that could be of use to crafty salesmen. Cookies reveal where else they have been browsing, allowing some guesses about their income bracket, age and sex. Their internet address can often be matched to their physical address: the richer the neighbourhood, the deeper the pockets, it may be assumed. Apple computer-owners are on average better-off than Windows PC users, and firms may offer them pricier options, as Orbitz, a travel website, is doing. Your mouse may also be squeaking on you: click too quickly from home-page to product page to checkout, and the seller can conclude that you have already decided to buy—so why offer you a discount?