Glossary
The AI app monetization glossary
Clear, vendor-neutral definitions of the 41 terms that come up when you monetize an AI app, from ad metrics like eCPM and fill rate to models like freemium and usage-based billing.
Built by the team behind the Monetzly ad-monetization SDK. Each term links to related concepts and the deeper guides.
Ad Impression
A single instance of an ad being served to a user.
Ad Inventory
The total ad space a publisher has available to sell.
Ad Relevance
How well an ad matches the user's current intent or context.
Ad Slot
A specific place where a single ad can appear.
ARPU
Average revenue per user over a period.
Brand Safety
Ensuring ads do not appear next to harmful or inappropriate content.
Churn
The rate at which users stop using or paying for an app.
Click-Through Rate (CTR)
The ratio of clicks to impressions for an ad.
Contextual Advertising
Serving ads based on the content being viewed rather than on personal tracking data.
Conversion Rate
The share of users who take a desired action, such as upgrading to paid.
CPM
Cost per mille — the price an advertiser pays per 1,000 impressions.
Customer Lifetime Value (LTV)
The total revenue expected from a user over their entire relationship with the app.
Direct-Sold Ads
Ad placements sold directly to advertisers rather than via a network.
eCPM
Effective cost per mille — estimated revenue per 1,000 ad impressions.
Fill Rate
The share of ad requests that are answered with a paying ad.
Fill-Rate Optimization
Techniques to raise the share of ad requests that return a paying ad.
First-Party Data
Data a company collects directly from its own users.
Freemium
A free base tier with paid upgrades for more features or higher limits.
Frequency Cap
A limit on how often a user sees ads over a period.
gRPC
A high-performance RPC framework using protocol buffers, often over HTTP/2.
House Ads
A publisher's own promotions used to fill unsold inventory.
In-Conversation Ads
Contextual ads placed inside an AI assistant's response stream rather than around the page.
Inference Cost
The compute cost of running an LLM to produce a response.
Large Language Model (LLM)
A neural network trained on large text corpora to generate and understand language.
Monetization
The set of methods by which an app generates revenue.
Monthly Active Users (MAU)
The number of unique users who engage with an app in a month.
Native Advertising
Ads that match the form and feel of the surrounding content.
Paywall
A gate that requires payment to access an app or its features.
Programmatic Advertising
Automated buying and selling of ad inventory via software.
Prompt
The input text that instructs an LLM what to do.
Real-Time Bidding (RTB)
Auctioning each ad impression in real time as it is served.
Retrieval-Augmented Generation (RAG)
Grounding an LLM's answers in retrieved external documents.
Session
A grouped sequence of interactions from one user conversation.
Sponsored Content
Content paid for by an advertiser and disclosed as such.
Sponsorship
A direct deal where a brand pays to be associated with a product or content.
Streaming (SSE)
Sending an LLM response incrementally, token by token, as it is generated.
Subscription
A recurring fee charged for ongoing access to an app.
System Prompt
Instructions that set an assistant's behaviour, separate from user messages.
Token Injection
Inserting ad content into an LLM's token stream as it is generated.
Usage-Based Billing
Charging in proportion to consumption, such as per token or request.
Viewability
Whether a served ad was actually seen by the user.