Startup & App Dev Glossary

RAG (Retrieval-Augmented Generation)

Retrieval-Augmented Generation (RAG) is a pattern where the system searches a document store, then asks an LLM to answer using the retrieved chunks — ideally with citations.

Embeddings

Embeddings are numeric vectors that represent text (or images) so similar meanings sit close together. RAG uses them to find relevant chunks.

AI Agent

An AI agent is a system where a model chooses actions (tools) in a loop until a job is done or a budget is hit — not a single chat completion.

Prompt Injection

Prompt injection is an attack where untrusted input (user text or a retrieved document) overrides or subverts the system instructions given to an LLM.

AI SaaS

AI SaaS is multi-tenant software whose core paid job is performed by a model API, with accounts, plans, and a usage cap.

MCP (Model Context Protocol)

Model Context Protocol (MCP) is an open standard for exposing tools and data to AI clients (IDEs, agents) through a consistent server interface.

AI MVP

An AI MVP is the smallest product that lets real users complete one AI-powered job — with accounts, a hosted model, and a usage cap.

Fine-Tuning

Fine-tuning is training a base model further on your examples so it better matches a style or task. It does not automatically know your latest documents.

MVP (Minimum Viable Product)

A Minimum Viable Product (MVP) is the simplest version of a product that can be released to early users to validate core assumptions, gather feedback, and begin learning — with the minimum amount of effort and cost.

PRD (Product Requirements Document)

A Product Requirements Document (PRD) is a document that describes what a product or feature should do — the problem it solves, who it's for, and what functionality it needs — before development begins.

User Story

A user story is a short, structured description of a software feature from the perspective of the end user, explaining who wants it, what they want, and why.

NPS (Net Promoter Score)

Net Promoter Score (NPS) is a customer loyalty metric based on a single question: 'How likely are you to recommend [product] to a friend or colleague?' on a scale of 0–10.

Product-Market Fit (PMF)

Product-market fit (PMF) is the degree to which a product satisfies a strong market demand — the state where your product is so valuable that users naturally recommend it and return to it.

North Star Metric

A North Star Metric (NSM) is the single, primary metric a company uses to measure the core value it delivers to customers — and by extension, predict long-term business health and growth.

OKR (Objectives and Key Results)

OKRs (Objectives and Key Results) is a goal-setting framework where an Objective defines what you want to achieve (qualitative) and Key Results define how you'll measure success (quantitative).

AI Prototype

An AI prototype is a clickable application produced mostly by an AI web builder or coding agent. It is for learning the flow and getting feedback — not a substitute for production engineering.

MRR (Monthly Recurring Revenue)

Monthly Recurring Revenue (MRR) is the predictable, normalized monthly revenue generated from all active subscriptions. It's the north star metric for SaaS companies.

ARR (Annual Recurring Revenue)

Annual Recurring Revenue (ARR) is the yearly equivalent of your recurring subscription revenue. It's MRR × 12 and is the primary metric investors use to value SaaS companies.

CAC (Customer Acquisition Cost)

Customer Acquisition Cost (CAC) is the total cost of acquiring one new paying customer, including all marketing and sales spend.

LTV (Lifetime Value)

Customer Lifetime Value (LTV or CLV) is the total predicted revenue you'll earn from a customer over the entire duration of your relationship.

Churn Rate

Churn rate is the percentage of customers (or revenue) that cancels or doesn't renew in a given time period. It's the single most important retention metric for subscription businesses.

ARPU (Average Revenue Per User)

Average Revenue Per User (ARPU) is the average monthly revenue generated per paying customer. It's the building block for LTV, MRR projections, and pricing decisions.

Net Revenue Retention (NRR / NDR)

Net Revenue Retention (NRR), also called Net Dollar Retention (NDR), measures the percentage of recurring revenue retained from existing customers over a period, including expansions and excluding new customers.

SaaS (Software as a Service)

Software as a Service (SaaS) is a software distribution model where applications are hosted in the cloud and provided to customers over the internet on a subscription basis, rather than installed locally.

B2B vs B2C

B2B (Business-to-Business) refers to products or services sold to other businesses. B2C (Business-to-Consumer) refers to products sold directly to individual consumers.

Startup Runway

Startup runway is the number of months a startup can continue operating before running out of cash, given its current burn rate and cash balance.

VC (Venture Capital)

Venture Capital (VC) is a form of private equity financing where investors provide funding to early-stage, high-growth startups in exchange for equity ownership, with the expectation of a significant return on exit.

Technical Debt

Technical debt refers to the implied cost of future rework required when shortcuts or suboptimal solutions are chosen during software development for the sake of speed.

API (Application Programming Interface)

An API (Application Programming Interface) is a set of rules and protocols that allows different software applications to communicate with each other — like a contract defining how one piece of software can request data or actions from another.

Row Level Security (RLS)

Row Level Security (RLS) is a PostgreSQL feature that controls which rows in a database table a user can read, insert, update, or delete — enforced at the database level, not the application layer.

Webhook

A webhook is an HTTP callback — a real-time notification sent from one application to another when a specific event occurs, without the receiving application needing to continuously poll for updates.

Sprint

A sprint is a fixed-length, time-boxed development cycle in Agile/Scrum methodology — typically 1 or 2 weeks — during which a defined set of features or tasks are built, tested, and delivered.

Multi-tenancy

Multi-tenancy is an architecture where a single instance of a software application serves multiple customers ('tenants'), with each tenant's data logically isolated from others — sharing the same infrastructure but with strict separation.

React Native

React Native is an open-source framework by Meta that lets developers build native mobile apps for iOS and Android using JavaScript and React — sharing one codebase across both platforms.

Supabase

Supabase is an open-source Backend-as-a-Service (BaaS) that provides a PostgreSQL database, authentication, file storage, real-time subscriptions, and edge functions — positioned as an open-source alternative to Firebase.

Expo

Expo is a framework and platform built on React Native that simplifies mobile app development with managed tooling, cloud builds (EAS), over-the-air updates, and pre-built native modules.

RevenueCat

RevenueCat is a subscription infrastructure platform that abstracts App Store and Google Play billing — handling receipt validation, subscription status, trials, and analytics through a single SDK and API.

No-Code

No-code development uses visual builders and drag-and-drop interfaces to create applications without writing traditional code — platforms include Bubble, Webflow, Adalo, and Glide.

Production-Ready

Production-ready software is an application you would let strangers create accounts on: tenant-safe data, secrets kept off the client, a deploy you can roll back, and a core loop that works when the happy path fails.

ASO (App Store Optimization)

App Store Optimization (ASO) is the process of optimizing a mobile app's listing to rank higher in App Store and Google Play search results and convert more viewers into downloads.

Product-Led Growth (PLG)

Product-Led Growth (PLG) is a go-to-market strategy where the product itself drives user acquisition, conversion, and expansion — users discover, try, and buy the product without needing a sales team.

Stripe Connect

Stripe Connect is Stripe's API for marketplaces and platforms that need to move money between multiple parties — enabling split payments, seller payouts, and platform fees.