Real Time Bidding or RTB is a process being used by more and more ad servers. RTB sends out simultaneous ad requests to all eligible advertisers at the same time and the advertiser that responds with the highest bid within the allotted time frame is chosen to deliver the ad. This process has the potential to increase the fill rate for publishers since all advertisers are given an equal chance to bid on an ad opportunity rather than a standard waterfall scenario where each advertiser is only called if the advertiser above them in the waterfall declines to fill the ad request.

Typically when an ad server is using a RTB setup they require requests to be sent in a specific format according to the IAB RTB specification. In these instances the advertiser knows they are participating in a RTB system, but some ad servers utilize a RTB system without requiring requests to be sent according to the IAB specification, and in those instances the advertiser may not know they are participating in a RTB system.

Although a RTB setup gives all advertisers an equal opportunity to win an ad request, there is a potential downside if the advertiser is not aware that they are part of a RTB system. The negative impact can be on the use rate.

The use rate is defined as the percentage of ads displayed/videos started compared to the amount of filled ads returned to the publisher. If an advertiser is sending a high percentage of filled requests to the publisher, but not many of them are being used the advertiser may begin to fill less ad requests from this particular publisher. If the advertiser is participating in a RTB system then a low use rate can be expected if they are not the highest bidder. For example if Advertiser ‘A’ is returning a high percentage of filled ads, but Advertiser ‘B’ is returning ads with a higher bid then the publisher would never be sent the filled ad response from Advertiser ‘A’ and thus Publisher ‘A’ would show a low use rate.

This scenario can weaken a publisher’s relationship with an advertiser and impact their fill rate and revenue, so it is important for a publisher to understand how their ad server functions (for example do they use RTB) and to communicate this with their advertisers. You may find that there are some advertisers who choose to not receive ad requests from a RTB system.

RTB can have a positive impact on a publisher’s fill rate and revenue, but it is important to communicate the environment that your ad server functions within so advertisers can properly analyze and interpret the data for the best fill rate and revenue opportunities.