Ad Serving

AdTech is a complex system that involves many components but you can devide them into two parts:

• DSP (Demand Side Platform): server for the advertisers to place bids and serve ads to the users
• SSP (Supply Side Platform): server for the publishers to sell the inventory to the advertisers

Advertisers want to reach the right users with their ads efficiently, and publishers want to sell the inventory to the advertisers at the highest price. Here is the simplified flow of how the ad serving works:

1. User → SSP: After receiving traffic from a user, the publisher sends an ad request to the SSP.
2. SSP → DSPs: The SSP broadcasts this request to multiple DSPs to solicit bids simultaneously.
3. DSPs → SSP → User: Once the SSP collects the bids from each DSP, it chooses the highest one and returns the winning ad to the user.

This entire process is called RTB(Real-Time Bidding), and it is the most common way to serve ads to the users nowadays. Often the ad request has a strict timeout limit, so the ad serving needs to be done in a very short time while choosing the right ad for the user. Also sometimes server can be under high traffic, so it needs to be scalable to handle the traffic.

                                                ┌───────┐
                                          ┌────►│ DSP A │
┌────────┐    Request     ┌───────┐ Bid   │     └───────┘
│  User  │───────────────►│  SSP  │───────┼────►│ DSP B │
│ (Pub)  │◄───────────────│       │◄──────┼─────│       │
└────────┘   Winning Ad   └───────┘ Win   │     ┌───────┐
                                          └────►│ DSP C │
                                                └───────┘