Podcast Advertising Glossary

Learn key terms relevant to podcast advertising

Updated over a week ago

New to podcast advertising? Learn the lingo with our handy glossary.

Ad script

The key messages an advertiser would like to deliver in their advert.


The total spend allocated to a single campaign

Campaign duration

The period of time a specific advertising campaign will run for. Can be set manually by advertiser or automatically by Acast.

CPM rate

Cost per mille (CPM) or ‘cost per thousand’ is the amount an advertiser pays per 1,000 impressions for its ads.


Call to action (CTA) refers to the next step you want your audience to take, for example to visit your website or use a promo code

Delivered Impressions

The total count of impressions delivered for this flight or campaign - these are IAB valid impressions (i.e. they have been filtered based on the Interactive Advertising Bureau 2.1 measurement standard)

Downloads/Listens (IAB)

Acast follows IAB-certified methods of calculating Listens and Downloads. A Listen/Download is valid according to the Interactive Advertising Bureau (IAB) if it meets the following criteria:

- Minimum download: At least 60 seconds of the episode was downloaded
- User Agent filter: Acast uses the IAB/ABC International Spider & Bots List to remove invalid user agents
- IP address filter: Acast uses the TAG Data Center IP list to remove non-human traffic
- 24-hour window: Only count one listen per listener, per episode, over a 24-hour period

Dynamic Ad Insertion

The process of ‘stitching’ ads into podcast content in real time, instead of the advert being ‘baked’ into the audio file permanently. The benefit is that the ads can be swapped for new creative or new advertisers at any time. All Acast’s ads and sponsorship are dynamically inserted at the point the listener hits play or download.


Forecasting is used to predict the number of impressions that will be delivered for a campaign based on the targeting rules

Frequency Capping

The maximum number of times per week that a listener hears a specific ad


Also known as 'Sponsorships'. Ads read by the host or producer of the podcast and dynamically inserted into the content. Not available through self-serve and must be purchased directly through the Acast sales team


The Interactive Advertising Bureau (IAB) is an advertising business organization that develops industry standards, conducts research, and provides legal support for the online advertising industry.

IAB advertising categories

Category codes that can be applied to an advertiser in an ad server, so that competing brands don't advertise next to each other, or so a campaign can be targeted away from content an advertiser may want to avoid.

IAB compliant/certified

When you hear a company say they’re IAB-certified or IAB-compliant, it means they follow a number of guidelines put in place by the Interactive Advertising Bureau (IAB) to report accurate data around things like listens and downloads. ‘Certified’ means they have been awarded direct certification by the IAB, while ‘compliant’ means they adhere to the standards, but have not yet received official certification. Acast is IAB-certified.


An ‘impression’ is defined as being one user who, while using web or media content, was presented with an advertisement. Acast is compliant with the IAB Podcast Measurement Technical Guidelines Version 2.1 for Ad Delivery. Valid ad delivery may only be counted if the entire ad file was downloaded in an IAB valid download.
To give an example - a listener clicks the “download” button on their app for the latest episode of The Intelligence. The entire episode is downloaded. All ads stitched into the episode are counted as impressions.
If it’s a progressive download or stream, ads are only counted if the entire ad is served. In other words - Listener clicks the “play” button on their app for the latest episode of The Intelligence. The app requests the start of the episode and delivers the pre-roll ad. The pre-roll ad is counted as an impression. Later, the app stops requesting the episode and does not reach the mid-roll ad — as no mid-roll ads were served, they are not counted as impressions.

Impression Goal

The maximum number of times a given campaign's creatives will be heard.

Mid-roll ad

When a dynamic ad is inserted in the middle of a podcast's episode.


An audio file that is downloaded or streamed, and listened to on a smartphone or computer, usually via an RSS feed


A podcast player or software used to play podcasts, such as Apple Podcasts or Spotify. Listeners can follow your show on these apps and receive notifications when there are new episodes.

Post-roll ad

When a dynamic ad appears at the end of a podcast's episode.

Pre-roll ad

When a dynamic ad appears at the beginning of a podcast's episode.


30-second audio ads crafted by the advertiser which are inserted into podcast episodes through dynamic ad insertion

Programmatic advertising

The use of software to automatically purchase and insert ads in a particular medium, rather than the traditional process involving human negotiations and manual insertion orders. In short, it's an automated way to buy and insert ads

Third party tracking

External vendors supported by Acast's self-serve platform which allow for pixel-based tracking of digital attribution, uplift, and conversion

Unique Impressions

Represents total unique users (devices) that heared the ad once or multiple times

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