Welcome to the Tapp Glossary. This is your definitive guide to the acronyms and technical terms used in mobile app growth, referral marketing, and viral engineering. Use the index below to jump to a specific term.
Index
A | C | D | E | F | K | L | M | O | R | S | UA
App Links
Android App Links are the Google-specific version of deep links. They are standard web links (HTTP/HTTPS) that are verified to belong to your app. When a user with your app installed clicks an App Link, it opens the specific content in your app directly instead of in a web browser.
Learn More: Deep Links vs. Dynamic Links vs. Universal Links
API (Application Programming Interface)
An API is a set of rules and protocols that allows different software applications to communicate with each other. It’s the mechanism through which you can programmatically interact with a service like Tapp to generate referral links or track events.
ASO (App Store Optimization)
ASO is the process of optimizing a mobile app’s listing in an app store (like the Apple App Store or Google Play Store) to increase its visibility and drive more downloads. This includes optimizing the app title, keywords, screenshots, and reviews.
C
CAC (Customer Acquisition Cost)
CAC is the total cost a business spends to acquire a new customer. A primary goal of referral and viral loops is to lower the blended CAC by acquiring new users for free or at a much lower cost than paid advertising.
CPA (Cost Per Action)
CPA is an affiliate or referral payout model where you pay a partner only when a user they refer completes a specific, valuable action *after* installing the app (e.g., creating an account or starting a trial). This model prioritizes user quality over sheer install volume.
Learn More: CPI vs. CPA vs. RevShare: Choosing the Right Payout Model
CPI (Cost Per Install)
CPI is an affiliate or referral payout model where you pay a partner a flat fee for every app install they generate. While simple to track, it carries a higher risk of attracting low-quality users who do not engage with the app.
Learn More: CPI vs. CPA vs. RevShare: Choosing the Right Payout Model
D
Deep Link
A deep link is any link that directs a user to a specific piece of content *inside* a mobile app they already have installed, bypassing the home screen. For example, a link that opens directly to a specific product page within a shopping app.
Learn More: Deep Links vs. Dynamic Links vs. Universal Links
Deferred Deep Linking
Deferred Deep Linking is the technology that makes modern mobile referrals and viral loops possible. If a user clicks a link but does not have the app installed, this technology first directs them to the App Store to install the app, and then, upon first open, routes them to the specific in-app content they were originally meant to see. It “defers” the deep link until after the installation is complete.
Learn More: Deep Links vs. Dynamic Links vs. Universal Links
E
EPC (Earnings Per Click)
EPC is a key metric used by affiliates to measure the financial performance of a program. It is calculated by dividing the total commissions earned by the total number of clicks sent. Sophisticated affiliates prioritize programs with a high and reliable EPC.
F
FDL (Firebase Dynamic Links)
FDL was a free deep linking service from Google that is being shut down in 2025. It allowed developers to create smart links that could route users to specific content within an app, even if the app had to be installed first.
Learn More: The Ultimate Guide to Firebase Dynamic Links Deprecation
K
K-Factor (Viral Coefficient)
The K-factor is the primary metric used to measure the virality of a product. It represents the average number of new users that each existing user successfully brings in. It is calculated with the formula K = i * c, where ‘i’ is the invitation rate and ‘c’ is the conversion rate.
Learn More: The Engineer’s Guide to Creating Viral Loops for App Growth
KPI (Key Performance Indicator)
A KPI is a measurable value that demonstrates how effectively a company is achieving key business objectives. For a referral program, KPIs include Invite Rate, Conversion Rate, and overall ROI.
L
LTV (Lifetime Value)
LTV is a prediction of the net profit attributed to the entire future relationship with a customer. For a referral program to be profitable, the LTV of a referred customer must be greater than the CAC.
M
MMP (Mobile Measurement Partner)
An MMP is a third-party company that provides attribution and analytics services for mobile apps. They help app marketers understand which campaigns are driving installs and in-app events.
O
OS (Operating System)
The OS is the software that manages all of the hardware and software resources of a computer or mobile device. The two dominant mobile operating systems are Apple’s iOS and Google’s Android.
R
RevShare (Revenue Share)
RevShare is an affiliate or referral payout model where you give a partner a percentage of the revenue generated from the users they refer. This model perfectly aligns incentives between the app and its partners.
Learn More: CPI vs. CPA vs. RevShare: Choosing the Right Payout Model
ROI (Return on Investment)
ROI is a performance measure used to evaluate the efficiency or profitability of an investment. It is calculated by dividing the net profit from an investment by its cost.
S
SDK (Software Development Kit)
An SDK is a collection of software development tools in one installable package. The Tapp SDK is a small library of code that you install in your mobile app to enable our tracking and attribution features.
SEO (Search Engine Optimization)
SEO is the practice of increasing the quantity and quality of traffic to your website through organic search engine results.
U
Universal Links
Universal Links are Apple’s implementation of deep links for iOS. They are standard web links (HTTP/HTTPS) that, when tapped, can reliably open your app directly to specific content instead of opening the link in Safari.
Learn More: Deep Links vs. Dynamic Links vs. Universal Links
UGC (User-Generated Content)
UGC is any form of content, such as images, videos, text, and audio, that has been posted by users on online platforms. UGC is the engine that powers social viral loops, where the content itself becomes the marketing vehicle.
Learn More: Beyond Referrals: Using Content and Social Loops for App Virality
UI (User Interface)
UI refers to the visual elements of a device or application, including screens, buttons, icons, and toggles, through which a user interacts with the product.
UX (User Experience)
UX refers to the overall experience a user has when interacting with a product, especially in terms of how easy or pleasing it is to use. A frictionless UX is critical for a high-performing referral program.