What Is In-App Advertising? Formats and How It Works

What is In-App Advertising?

In-app advertising is the practice of showing ads inside mobile applications and games, using formats such as banners, interstitials, rewarded video and native units, bought by advertisers directly or through programmatic channels.

Also known as: mobile in-app advertising, app advertising

How it works

When a user opens an app, the app can request an ad from one or more demand sources through an SDK (a software development kit, the code library that connects the app to ad technology). Those sources may include direct campaigns, programmatic buyers bidding in real time, or curated deals. The winning ad is returned and displayed in a placement the app developer has designed.

From a buyer's point of view, in-app inventory is defined by the app itself, its category, the device, the geography and the ad format. Common formats include:

Banners and rich media, which sit within the app screen and can include interaction or animation.
Interstitials, full-screen ads shown at natural breaks, such as between game levels.
Rewarded ads, which the user chooses to watch in exchange for an in-app benefit.
In-stream video, played within video content in the app.
Overlays, which appear on top of app content.
Offerwalls, which list actions a user can complete for a reward, often paid on a cost-per-action (CPA) basis.

Why it matters

Much of what people do on their phones, from gaming to shopping to streaming, happens inside apps rather than in a browser, so advertisers who want to reach mobile audiences need a plan for app inventory. Apps also offer formats with strong attention, such as full-screen and opt-in units, that are harder to replicate on the web.

At the same time, in-app buying has its own challenges. Measurement works differently from the browser, inventory quality varies between apps, and fraud such as app ID spoofing can creep in. Buyers rely on viewability measurement, invalid traffic filtration and supply chain transparency to buy with confidence. For the app owner's side of the story, see mobile app monetization.

Example

Illustrative example. A consumer brand wants to reach casual gamers. Rather than buying banners across every app, its agency sets up a curated deal for rewarded video and interstitial placements in puzzle and word games, targeted to specific countries and devices. The rewarded format lets users choose to watch, and the interstitials run only at level breaks, so the brand gets full attention without interrupting play.

IncrementX perspective

IncrementX represents mobile app publishers and helps connect their inventory with advertiser demand. Its Mobile App channel covers rich media, overlay and in-stream formats, plus rewarded, interstitial and CPA offerwall. Through mobile app publisher representation, the focus is on packaging app inventory so brands, agencies, DSPs and programmatic buyers can access it through direct demand, curated deals, PMP and programmatic channels.

In-App Advertising FAQs

Mobile web ads run in a browser on a website, while in-app ads run inside an installed app through a software development kit (SDK). Apps identify inventory by app rather than by domain, and formats like rewarded video are far more common in apps.

A rewarded ad offers the user something in the app, such as an extra life or bonus content, in return for choosing to watch or interact with an ad. Because the user opts in, it tends to feel less intrusive.

Yes. App inventory is widely sold through programmatic channels, including open auctions and curated deals such as private marketplaces, as well as through direct buys.

It can be. App ID spoofing, where a low-quality app pretends to be a better-known one, is one example of invalid activity, which is why supply chain checks and IVT filtration matter.

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In-App Advertising