Dynamic Ad Insertion & AdTech Guide: Most Popular Terms

Confused by CPMs, fill rates, impression tracking, and programmatic advertising? Here's a simple guide to some of the more frequently-used terms you'll encounter when selling podcast ads through Captivate Marketplace.

Dynamic Ad Insertion (DAI)

The technology that allows ads to be inserted into podcast episodes automatically when a listener downloads or streams an episode. Instead of permanently embedding an ad into your audio, DAI lets ads be easily replaced and removed. This means you can continue earning revenue from old episodes long after they're published.

Pre-roll, Mid-roll & Post-roll

• Pre-roll: Ad at the beginning of an episode.
• Mid-roll: Ad inserted during the episode.
• Post-roll: Ad at the end.

Mid-roll placements often command higher rates because listener engagement is typically strongest since the ads play “in-episode”.

Ad Inventory

The advertising space available in your podcast. For example, if you have 1 pre-roll, 1 mid-roll, and 1 post-roll, you have three pieces of ad inventory available for advertisers to purchase. If you allowed two Ad units per Ad location then you would have six pieces of ad inventory available.

Ad Opportunity

An ad opportunity is a chance to deliver an advertisement to a listener. Think of it as an available advertising slot.

For example, if your episode has 1 mid-roll ad slot and the episode receives 1,000 downloads, that creates 1,000 ad opportunities.

If your episode has 1 pre-roll, 1 mid-roll, and 1 post-roll and receives 1,000 downloads, that creates 3,000 ad opportunities.

Fill Rate

The percentage of available ad inventory that is actually sold. For example, if you have 1,000 available ad opportunities and advertisers purchase 700 of them, your fill rate is 70%. Ad revenue depends not just on your CPM, but on how much inventory gets filled.

CPM Cost Per Mille

This stands for Cost Per Mille (1,000 impressions) and is the amount an advertiser pays for every 1,000 ad impressions delivered. A $20 CPM means an advertiser pays $20 for every 1,000 impressions.

Impression

An ad impression occurs when an ad is successfully delivered to a listener. This is typically the metric used to calculate advertising revenue.

Programmatic Advertising

The automated buying and selling of advertising inventory through technology platforms rather than direct negotiations. Advertisers browse available inventory and purchase placements without having to contact podcasters individually. Ads are then inserted into the podcaster’s available ad slots.

Targeting

The ability to serve ads to specific audiences. This can be geographic targeting (country/region), device targeting (OS/hardware), and language targeting

Brand Safety

Controls that help ensure advertisers and creators are paired appropriately. This can include content category restrictions and advertiser exclusions. This is key to ensure your podcast audience doesn’t hear inappropriate ads (so, betting ads on kids' podcasts, for instance).

Revenue Share

The percentage of advertising revenue paid to the podcaster after any platform fees / marketplace fees are deducted.

Updated on: 24/06/2026