Definition:
RTB (Real Time Bidding) consists of an auction in which ad impressions are sold and bought and transactions are made in just seconds. When the advertiser manages to win an auction, their advertising is displayed instantly, on the website in question.
For the execution of the RTB, there are support platforms such as Ad Exchange and Supply Side Platform (SSP).
How Real Time Bidding (RTB) works
When any user enters a website, the Ad Exchange receives a corresponding offer request containing demographic, location, browser history, etc.
Later, the ad exchange passes the requests for offer to its list of advertisers, who will be bidding in real time to place their ads on that page. They are transactions that happen in a very short time.
To give an example of what the RTB is, if I now type in my browser the page of a digital newspaper, during the tenths of a second it takes to load the page is when the transactions occur. Thus, once all the components of the web have been loaded, the ads of the one who has bid the highest will appear.