The advertiser that bids the higher amount with the media company wins.
Bidding is a way for publishers to establish an impartial and open auction over their ad inventory by offering every ad opportunity to multiple buyers in real time.
The buyer willing to pay the highest price has a chance to win every time.
Real time bidding is much more the protocol that supports the bidding process.
When a publisher sells advertisement to an ad exchange, the ad exchange runs an auction among the bids of ad network and returns the winner to the publisher which becomes the ad impression for the website visitor.
Each bid is valid for a certain amount of time. Any impressions served on bids older than this lapse time is generally not paid.
A Bid Request is a request sent by the market place (Google) to the buyer application that describes an impression being auctioned.
A response sent by the buyer application to the market place (Google) that describes the bid and includes an HTML snippet for the associated creative.