Startup & App Dev Glossary
Every term you need to know — SaaS metrics, product concepts, engineering jargon, and fundraising vocabulary, explained simply.
Product
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.
SaaS Metrics
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.
Business Model
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.
Fundraising
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.
Engineering
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.