The third and most recent major development that shaped the advertiser-publisher ecosystem started occurring in the late 2000s when widespread adoption of RTB (real time bidding) technology took place. Also referred to as programmatic bidding, RTB allowed companies representing buyers and sellers to bid on the price to show an ad to a user every time a banner ad is loading. When a page loads during a user visit, there are thousands of bids occurring from advertisers to serve an ad to that user, based on each company's individual algorithms. With this most recent change in the industry, more and more ads are being sold on a single-impression basis, as opposed to in bulk purchases.