With traditional or direct ad buying you purchase advertising space on a website or in a traditional publication directly from the publisher.
You negotiate the price, pick the placing and the date the ad will run, and for how long the ad will be shown to the publisher’s readers. It involves people talking with people, and the process can take time, as ad copy is sent back and forth for approval. Results are calculated manually and provided to the buyer when they become available. Ads are optimized manually based on the data.
The most common example of traditional ad buying is buying ad space on a site like the Wall Street Journal, New York Times, or Boston.com. Everyone who visits these websites will see your ad, regardless of whether they could be interested in your product/service or not.
Purchasing programmatic advertising, on the other hand, is very similar to Facebook or Google where the ads are bought and sold through an automated process through a dashboard. Real-time optimization occurs and KPI data are available as it comes in. There is no need to interact with any salespeople at the publishers.
Unlike in the first example, your ad is only shown to the website visitor who matches the behavioral or demographic characteristics of your ideal customer, increasing the likelihood that they will click on your ad.