Podcast Advertising Glossary: 20 Terms Every Host and Advertiser Should Know

Podcast advertising is a $2.86 billion business in the US, up 17.6% in 2025,^[3] and Americans now spend around 773 million hours a week with podcasts.^[2] A market that size has its own vocabulary, and most of it is not the display-ad jargon you will find in a generic marketing glossary. This is the short list: the 20 terms that come up in real sponsorship conversations, ad-ops emails, and hosting dashboards in 2026, each defined in a single paragraph you can quote on its own.

Every term below is its own anchor, so you can link straight to a definition. Jump to any of them from the contents list, and follow the in-text links to dig into the ones with a full guide.

Updated July 2026: rebuilt around the terms that matter today. Dynamic ad insertion, server-side insertion, IAB downloads, attribution, and programmatic buying were added; generic display-advertising terms that were not specific to podcasting were removed.

Ad Formats

An ad format is set by two things: who voices the ad and where it falls in the episode. Those two choices decide how much a slot costs and how well it converts, long before anyone writes a word of copy. The five formats below are the vocabulary every rate card is built from, so they are usually the first terms a new sponsor asks about.

Host-Read Ad

A host-read ad is read aloud by the podcast host in their own voice, usually from talking points rather than a word-for-word script, so it lands as a personal endorsement. Host-read ads consistently outperform produced spots on recall and trust, which is why advertisers pay a premium for them. They can be baked in or delivered through dynamic ad insertion.

Announcer-Read Ad

An announcer-read ad is a professionally produced spot voiced by someone other than the host and dropped into the episode as a finished audio file. It gives the advertiser total control over the message and works well with dynamic ad insertion, but it carries none of the host’s credibility, so it usually converts below a host-read ad.

Pre-Roll Ad

A pre-roll ad runs at the very start of an episode, before the main content. It captures every listener who presses play, but attention is still settling, so pre-roll is priced below mid-roll. It is the most common slot for a short brand or sponsor mention.

Mid-Roll Ad

A mid-roll ad runs partway through an episode, after the audience has committed to listening. It is the most valuable slot in podcasting because engagement is highest and listeners are least likely to skip. Most premium CPM rates are quoted for mid-roll.

Post-Roll Ad

A post-roll ad runs at the end of an episode, after the main content has finished. Fewer listeners stay to hear it, so it is the cheapest slot, but the ones who do are the most engaged part of your audience. Post-roll pairs well with a direct call to action.

Ad Delivery

Ad delivery is the mechanism that gets an ad into the file a listener downloads, and it is where podcast advertising has changed the most in the last decade. The move from ads recorded into the episode to ads inserted at the moment of download is what made targeting, back-catalog monetization, and programmatic buying possible at all. These terms explain how a modern podcast ad actually reaches an ear.

Baked-In Ad

A baked-in ad is recorded permanently into the episode’s audio file, so it appears in every download for the life of that episode. Baked-in ads are simple and never break, but they cannot be changed, targeted, or removed once published, which is the problem dynamic ad insertion was built to solve. They are also called embedded ads.

Dynamic Ad Insertion (DAI)

Dynamic ad insertion is technology that stitches ads into a podcast at the moment of download rather than baking them into the file, so the same episode can serve different ads to different listeners. DAI lets you swap sponsors, target by location or device, expire a campaign on a set date, and monetize your entire back catalog at once. It is the foundation of nearly all modern podcast advertising and is delivered through server-side ad insertion at points set by ad markers. Dynamic ad insertion now accounts for more than 90% of US podcast ad revenue.^[3]

Server-Side Ad Insertion (SSAI)

Server-side ad insertion is the delivery method behind dynamic ad insertion: the podcast host’s server assembles the chosen ad and the episode into one continuous audio stream before sending it to the listener. Because the ad and content arrive as a single file, SSAI is far harder for ad blockers to strip out than client-side insertion, which is why it is the podcast standard.

Ad Marker

An ad marker is a timestamp embedded in an episode that tells dynamic ad insertion exactly where a pre-roll, mid-roll, or post-roll ad should be placed. Setting markers thoughtfully, at natural breaks rather than mid-sentence, is the difference between an ad that feels native and one that jars.

Programmatic Podcast Advertising

Programmatic podcast advertising is the buying and selling of ad inventory automatically through a marketplace, rather than negotiating each sponsorship by hand. It relies on dynamic ad insertion to fill slots in real time and lets small shows earn ad revenue without a sales team, though at lower CPMs than a directly sold host-read ad.

Measurement

Measurement is how an audience and an ad’s delivery get counted, and it is the foundation every price rests on. A rate card is only as trustworthy as the download numbers behind it, so serious advertisers scrutinize how a show counts before they ever debate what it charges. These are the terms that come up the moment a buyer asks, “how do you actually know?”

IAB Certified Download

An IAB certified download is one counted according to the IAB Podcast Measurement Technical Guidelines, the industry standard that filters out bots, duplicate requests, and partial downloads.^[1] Advertisers trust IAB-certified numbers because they are comparable across hosts, unlike raw server hits, which can overcount an audience by a wide margin.

Download vs. Listen

A download is a request for the episode file; a listen is confirmed playback of it. The two are not the same, and podcast ads are almost always priced and measured on downloads, not listens, because downloads are what a host can reliably count. Knowing the gap between them keeps you honest when you read an audience number.

Podcast Attribution

Podcast attribution connects a listener’s ad exposure to a later action, such as visiting a site or making a purchase, usually through a tracking pixel the advertiser places on their pages. It is how brands prove a podcast campaign actually worked, and its rise is what pulled direct-response advertisers into podcasting. Attribution is the practical answer to “did that ad pay for itself.”

Reach and Frequency

Reach is the number of unique listeners who heard an ad; frequency is how many times the average listener heard it. The two together describe a campaign far better than a single download count. High reach with low frequency builds awareness; lower reach with higher frequency drives action, which is why advertisers set a frequency target rather than just buying impressions.

Share of Ear

Share of Ear is an Edison Research metric measuring the percentage of daily audio listening time that a format or platform captures across the US population.^[2] In its 2025 data, podcasts made up about 20% of ad-supported audio listening and 10% of all daily time Americans spent with audio.^[2] It is the number podcast sellers cite to show how listening is shifting from radio and music toward on-demand audio.

Buying and Deals

Once the format is chosen and the audience is counted, a deal still has to be priced, papered, and honored. This is the commercial machinery of an ad buy: what a slot costs, how the agreement is documented, and what a host owes an advertiser when a campaign underdelivers. These terms are what turn an interested sponsor into a signed, delivered campaign.

CPM (Cost Per Mille)

CPM (cost per mille) is the price an advertiser pays per 1,000 downloads of an ad, and it is the standard unit for pricing podcast advertising. A $25 CPM on an episode with 10,000 downloads earns the host $250 for that slot. Mid-roll and host-read placements command the highest CPMs. We cover live rates in our guide to podcast advertising.

Rate Card

A rate card is the document a podcast gives potential advertisers, listing its ad slots and their CPMs or flat rates. It sets the anchor for negotiation rather than a fixed price, and a credible rate card is backed by IAB-certified download numbers. Our guide on how to get podcast sponsors walks through building one.

Insertion Order

An insertion order (IO) is the contract that confirms an ad buy: the flight dates, the ad slots, the promised impressions, and the total cost. Signing the IO is the point a sponsorship becomes real. It is also where a make good clause is defined, in case the campaign underdelivers.

Make Good

A make good is free replacement ad delivery a podcast owes an advertiser when a campaign falls short of the impressions promised on the insertion order. Rather than refunding cash, the host runs the ad in extra episodes until the shortfall is covered. Clear make-good terms protect both sides and signal a professional operation.

Podroll

A podroll is a cross-promotion in which one podcast recommends another, the podcast equivalent of a blogroll. Podrolls are usually traded between shows with similar audiences rather than sold, and some dynamic ad insertion platforms now automate them. They are one of the cheapest ways to grow an audience, since the recommendation reaches people who already listen to podcasts.

Frequently Asked Questions

What is dynamic ad insertion in podcasts?

Dynamic ad insertion (DAI) adds ads to a podcast at the moment of download rather than recording them into the file, so the same episode can serve different, targeted, swappable ads to each listener.

How are podcast ads priced?

Podcast ads are priced on a CPM basis, the cost per 1,000 downloads. A host multiplies its CPM by an episode’s download count to price a slot, and mid-roll and host-read placements command the highest rates.

What is the difference between baked-in and dynamically inserted ads?

A baked-in ad is recorded permanently into the episode and appears in every download forever. A dynamically inserted ad is added at download time and can be changed, targeted, or expired without re-editing the episode.

What counts as a podcast download?

The industry standard is the IAB-certified download, defined by the IAB Podcast Measurement Technical Guidelines, which filter out bots, duplicate requests, and partial downloads so numbers are comparable across hosts.

What is podcast attribution?

Podcast attribution ties a listener’s ad exposure to a later action, such as a site visit or purchase, usually through a tracking pixel. It is how an advertiser proves a campaign actually drove results.

The Bottom Line

Podcast advertising in 2026 runs on dynamic ad insertion, priced in CPM against IAB-certified downloads, and increasingly measured with attribution. Learn those four and the rest of this glossary falls into place. When you are ready to sell, our guides to podcast advertising and getting sponsors turn these definitions into a rate card, and our advertising calculator turns a CPM and a download count into a dollar figure.

Article Sources

Castos uses primary sources, industry standards bodies and original research, to support the facts in our guides.

1. IAB Technology Laboratory. “Podcast Measurement Technical Guidelines v2.1.” Accessed July 27, 2026. iabtechlab.com.
2. Edison Research. “Share of Ear.” Accessed July 27, 2026. edisonresearch.com.
3. IAB. “U.S. Podcast Advertising Revenue Study” (FY2025 results, reporting $2.86B in revenue and dynamic ad insertion at over 90% of ad revenue). Accessed July 27, 2026. iab.com.