Real-time bidding allows marketers to buy known audiences. The winner serves the advertisement, often customising it—so you may see more ads for convertible cars on a sunny day. The whole process generally takes some 150 milliseconds, or less than half the blink of an eye.
Real-time bidding makes it easy to aim ads at susceptible eyeballs. Firms such as John Lewis (a British department store), Zappos (an online shoe-seller) and Lenovo (a computer-maker) know that you have visited their websites because they dropped digital markers onto your computer. They then outbid others to reach you again. This is called “retargeting”.
Read more at The Economist
