Reference6 min read

Ad Monetization Glossary: Every Term Explained in Plain English

Ad tech loves jargon. This is the plain-English reference for every term you'll run into while monetizing an app, game, or website.

Ad Revenue Calculator Editorial·Updated August 2026·Figures from our published methodology

Ad tech accumulates jargon fast, and most of it gets used loosely. This page defines the terms you will actually run into while monetizing an app, game, or website — grouped by what they measure, not alphabetically, so related concepts sit next to each other. Jump to a section or just read straight through.

Money & measurement

eCPM (effective cost per mille)

Revenue per 1,000 ad impressions on mobile: (total revenue ÷ total impressions) × 1,000. The core metric for app and game monetization. Full explanation in the eCPM guide.

RPM (revenue per mille)

The web equivalent of eCPM, measured per 1,000 pageviews instead of impressions. A page can carry several ad slots, so pageviews (not impressions) are the denominator.

CPM (cost per mille)

What an advertiser agrees to pay per 1,000 impressions before fill or blending. This is a bid price, not what you actually earn — eCPM is what you actually earn.

CPC (cost per click)

Price paid per click rather than per impression. Common in performance campaigns; converted to an effective eCPM once you know click-through rate.

CPI (cost per install)

Price paid per app install rather than per impression or click. Used heavily in user-acquisition campaigns, distinct from the revenue side of monetization.

Fill rate

The share of ad requests that actually return a paid ad, from 0–100%. A network with a high quoted eCPM but low fill rate can earn less in practice than a lower-eCPM network that fills nearly every request.

ARPDAU (average revenue per daily active user)

Total daily revenue divided by daily active users. Useful for comparing monetization efficiency across apps of very different sizes, independent of raw user count.

LTV (lifetime value)

The total revenue, ad plus in-app purchase, a typical user generates over their entire time in the app. Used to set how much you can afford to spend acquiring a new user.

Ad formats

Rewarded video

A full video ad a user opts into in exchange for an in-app reward (currency, an extra life, a skip). The highest-eCPM mobile format because engagement is voluntary. See the rewarded vs interstitial guide.

Interstitial

A full-screen ad shown at a natural break in an app or game (level end, menu return). Pays well but can hurt retention if over-served.

Native ad

An ad styled to match the surrounding app or page content rather than looking like a distinct ad unit. Better eCPM than a banner, less disruptive than an interstitial, at the cost of design effort.

Sticky / anchor ad

A web ad format that stays fixed in the viewport (usually bottom of screen) as the user scrolls. The web equivalent of a mobile banner. See the web ad formats guide.

App open ad

A full-screen ad shown when a user opens or returns to an app, typically while the app is loading. High visibility, used sparingly to avoid feeling intrusive on every launch.

Networks & infrastructure

Ad network

A company that connects publishers (you) with advertisers, such as AdMob or AdSense. Sells your inventory using its own advertiser demand.

Mediation

A layer that sits above multiple ad networks and decides which one fills each impression, typically via waterfall or in-app bidding. See AppLovin MAX vs AdMob for how this plays out in practice.

Waterfall

A mediation setup where networks are tried in a fixed priority order, each with a set price floor, until one fills the request. Simple but static — it doesn’t adapt to which network would actually pay most for a given impression right now.

Header bidding / in-app bidding

An auction-based alternative to waterfalls where multiple networks bid on each impression simultaneously and the highest bid wins. Generally out-earns a waterfall because it captures real-time competition instead of a fixed priority order.

Price floor

The minimum price you’ll accept for an impression. Set too high and fill rate drops; set too low and you leave money on the table on your best inventory.

ads.txt

A text file at your domain’s root that publicly declares which ad networks are authorized to sell your inventory, preventing unauthorized resellers from spoofing your traffic.

Audience & targeting

Geo tier (Tier 1 / 2 / 3)

A bucket of countries grouped by advertiser demand. Tier 1 (US, UK, Canada, Australia) commands the highest eCPMs; Tier 3 (much of Asia, LatAm, Africa) the lowest, often by five to ten times for the same ad.

DAU / MAU

Daily active users and monthly active users. The ratio between them (DAU/MAU) is a common stickiness metric — higher means users return more often within a month.

IDFA (Identifier for Advertisers)

Apple’s per-device advertising identifier. Since iOS 14.5, apps must ask permission to access it under App Tracking Transparency. See the full ATT impact guide.

SKAdNetwork

Apple’s privacy-preserving framework for measuring ad campaign performance without per-user tracking, used as a fallback once IDFA access is limited by App Tracking Transparency.

Viewability

Whether an ad was actually visible on screen long enough to count as a real impression under industry standards (commonly 50% of pixels for 1 second). Low viewability inventory earns less and can get flagged by networks.

Missing a term you ran into elsewhere on the site? Check the FAQ or put your own numbers through the calculator to see how these pieces fit together.