In this example, we'll look at the process of buying ad space directly from the publisher. This is called a direct buy.

At an advertising agency, it's the job of a Media Planner to figure out where their

client's ads will run. So, if the client is selling pro-sports fan gear, then they'll

want to show ads on sites where sports fans hang out.

Once the Media Planner has picked the websites where they want to run their campaign, they'll

contact the publisher directly with an RFP, or Request For Proposal.

The RFP outlines campaign goals, run dates, and target audience. It also includes budget

details, like how many clicks or impressions they hope to get.. and how much the agency

is willing to spend.

When the publisher website receives the RFP, they'll review the list of requirements and

the agency's budget and compare it against their available inventory. Inventory refers

to the number of ad slots a publisher thinks they'll have available on specific pages on

a given day.

This can be tough to determine since publishers don't know exactly how many visitors will

come to their site, let alone which cat video will be most popular on a particular day.

While nobody can predict the future, publishers use prior trends to estimate how many visitors

will view pages on their website. This is called forecasting.

If the publisher has inventory that matches what the agency's looking for, they'll return

the RFP with a list of options and prices.

When the agency and publisher agree on the number of impressions or clicks, as well as

the cost, the agency creates an IO, or Insertion Order to seal the deal. The agency signs the

IO and sends it to the publisher. Once the IO is signed by both parties, it's considered

a legally binding contract.

After the campaign goes live, the publisher serves the client's ads as promised. And..

when the campaign is over, the publisher sends a bill for the ad space so the agency can

keep up their end of the deal.

And then, everyone is happy.