291 practical terms · See, feel, understand
291 terms
Product Requirements Document
A document that spells out what the product needs to do.
User Story
A way to define features in the form "As a user, I want to ...".
Persona
A fictional profile that represents your typical user.
User Flow
A visualization of the paths a user takes through your service.
Sitemap
A tree-shaped overview of every page in your service.
Information Architecture
Designing how information is categorized and laid out.
Scope
The boundaries of what features ship in this version.
Minimum Viable Product
A bare-bones product with just the essential features.
Proof of Concept
A prototype used to verify whether an idea is technically feasible.
Sprint
A focused 1–2 week cycle of work.
Backlog
A prioritized master list of everything to be done.
Epic
A large chunk of functionality that groups several user stories.
Specification
A document that defines exactly how a feature should behave.
Key Performance Indicator
A key metric used to measure the success of a service.
Objectives and Key Results
A framework for setting objectives and measurable key results.
Benchmarking
Analyzing competing services and applying what you learn.
Lean Canvas
A framework for capturing a business model on a single page.
Total/Serviceable/Obtainable Market
Total market → serviceable market → the slice you can realistically capture.
Product-Market Fit
The state where your product clearly fits the market's needs.
Pivot
Shifting the direction of a service based on market feedback.
Roadmap
A plan of upcoming development timelines and feature releases.
Milestone
A significant intermediate checkpoint in a project.
Stakeholder
Anyone who affects or is affected by the project.
UX Research
The practice of investigating user behavior and needs.
A/B Test
An experiment that compares two versions to pick the better one.
Funnel
The step-by-step flow from visit to conversion to payment.
Conversion Rate
The share of visitors who actually complete a target action (sign-up, purchase).
Retention
The rate at which users come back to a service.
Work Breakdown Structure
A structure that breaks a project down into small units of work.
Functional Spec
A document defining what output each feature produces for a given input.
Wireframe
A black-and-white skeleton that lays out structure without visual design.
Mockup
A high-fidelity mock with the final visual design applied.
Prototype
A clickable interactive mock, often built in Figma.
Design System
A unified set of UI rules covering colors, fonts, buttons, and more.
Style Guide
A documented reference for color codes, fonts, and spacing rules.
User Interface
The screen itself that users see and interact with.
User Experience
The overall experience a person has while using a service.
Hero Section
The large top area of a web page that forms the first impression.
Call to Action
An action-prompting button or phrase like "Get Started" or "Try Free".
Navigation Bar
The menu bar at the top of the page.
Footer
The bottom area of a page, often for contact info and legal links.
Card
A boxed UI component bundling an image, text, and buttons.
Modal
A popup that floats over the screen and captures focus.
Toast
A short notification that appears briefly in a corner of the screen.
Accordion
A collapse/expand UI often used for FAQs.
Carousel / Slider
Content slides that you swipe or click through horizontally.
Dropdown
A list of choices that unfolds downward when clicked.
Breadcrumb
Navigation that shows the trail like Home > Category > Detail.
Responsive Design
A layout that automatically adapts to desktop, tablet, and mobile screens.
Breakpoint
The screen-width threshold at which a responsive layout switches.
Grid System
A layout that aligns elements on a grid of columns and rows.
Padding / Margin
Inner spacing (padding) and outer spacing (margin).
Typography
Text styling — typeface, size, weight, line height, and more.
Color Palette
A unified set of colors used throughout a service.
Whitespace
Empty space between elements; generous whitespace feels premium.
Interaction
How the screen reacts to user actions like clicks, hovers, and scrolls.
Transition
A motion effect that smoothly bridges two states.
Accessibility (a11y)
Design principles that make a product usable by people with disabilities and older adults.
Dark Mode
A UI theme built around dark backgrounds.
Skeleton UI
A gray placeholder screen shown while data is loading.
Affordance
When the design itself hints at how to use it.
Visual Hierarchy
Guiding attention through size, color, and placement.
Gutter
The space between columns in a grid.
Divider
A horizontal line that separates content areas.
Badge
A small number or dot on an icon, often showing notification counts.
Tooltip
A small explanatory bubble that appears on hover.
Placeholder
Faint guiding text shown inside an input field.
Form Validation
Checking input values for correctness in real time.
Stepper
A UI that shows progress through Step 1 → 2 → 3.
Progress Bar
A bar that visualizes how far along a task is.
Spinner
A spinning icon that signals loading is in progress.
Bottom Sheet
A mobile panel that slides up from the bottom of the screen.
Floating Action Button
A circular action button floating at the bottom-right of the screen.
Hamburger Menu
A hidden menu that opens when you tap the three-line (≡) icon.
Sidebar
A fixed vertical menu on the left or right of the screen.
Sticky
An element that stays pinned on screen while you scroll.
Anchor Link
A link that scrolls to a specific section on the same page.
Hit Area / Tap Target
The actual tappable area of a button or link.
Overlay
A translucent layer that covers the screen.
Z-Index
The stacking order of elements — higher numbers sit on top.
Icon System
A consistent icon set used across the entire service.
Empty State
A helpful screen shown when there is no data to display.
Onboarding
The intro flow that teaches new users how to use the service.
Micro Interaction
Small feedback effects, like a heart popping when you tap Like.
Motion Design
Designing motion for screen transitions, element entrances, and more.
Color Contrast
Luminance difference between text and background — accessibility requires at least 4.5:1.
Auto Layout (Figma)
A Figma feature that auto-aligns and spaces elements.
Design Token
The smallest unit of a design system — variables for colors, spacing, etc.
Handoff
When designers hand designs and specs over to developers.
Inspect (Zeplin)
A tool for extracting exact values (spacing, color, font) from a design.
Affinity Map
A method of grouping research findings to surface patterns.
Moodboard
A board collecting colors, mood, and references to shape a design's feel.
Grayscale
Designing using only shades of gray, with no color.
Fidelity
The level of polish of a design: Lo-fi → Mid-fi → Hi-fi.
Redline
Annotations on a mock marking spacing and size values.
Pixel Perfect
Implementing a design without a single pixel of deviation.
Raster / Vector
Raster (pixels, JPG) vs vector (math, SVG). Vectors scale without blurring.
Retina Assets
Image scale factors for high-density displays.
Bleed
Laying out a design element so it reaches the very edge of the screen.
Above the Fold
The portion of a page visible without scrolling.
Scroll Jacking
Hijacking the native scroll behavior to apply custom effects.
Parallax
An effect where the foreground and background scroll at different speeds.
Full Bleed Image
An image that spans the full width of the screen edge-to-edge.
Gradient
A smooth blend between two or more colors.
Glassmorphism
A UI style that feels like frosted glass — blur plus translucency.
Neumorphism
A soft 3D UI style where elements look gently raised or pressed in.
Flat Design
A simple, 2D style with no shadows or depth.
Material Design
Google's design system, using shadows and depth to show hierarchy.
Cupertino Design
Apple's iOS style — blurred, translucent, minimal.
Negative Space
Intentionally empty space used to direct the viewer's attention.
Leading / Line Height
Spacing between lines of text, typically 1.4–1.6× the font size.
Kerning / Tracking
Kerning is spacing between specific letter pairs; tracking is overall letter spacing.
Fold
The line where the viewport ends before scrolling.
Splash Screen
The brief logo screen shown while an app is launching.
Walkthrough
Intro slides shown on first launch to introduce features.
Coachmark
An overlay that highlights a UI element and explains how to use it.
Snackbar
A bottom notification with an action button — an expanded toast.
Chip
A small capsule-shaped UI for tags or filters.
Avatar
A circular image or initials that represents a user profile.
Pagination
Splitting content across multiple pages you can navigate between.
Semantic Color
A color system where colors carry meaning, like red for error and green for success.
Primary / Secondary
Importance tiers for buttons and colors — primary is the most emphasized.
Destructive Action
Risky actions that are hard to undo, like delete or account removal.
Confirm Dialog
A re-confirmation popup like "Are you sure you want to delete?"
Inline Editing
A UI that lets you edit a value directly in place.
Drag & Drop
An interaction where you drag an element and drop it somewhere.
Kanban
A task board UI organized into To-do → In Progress → Done columns.
Data Table
A structured table that supports sorting, filtering, and pagination.
Sorting
Ordering a list ascending or descending by some criterion.
Filtering
Narrowing data down to only the items that match your criteria.
Search Bar
A search input field with a magnifying-glass icon.
Autocomplete
Suggesting queries automatically as you type.
Tag
A classification label attached to content.
Toggle
A switch UI that flips between on and off.
Radio Button
A circular selector that allows only one choice at a time.
Checkbox
A square selector that allows multiple choices at once.
Date Picker
A calendar UI for picking a date.
Time Picker
A UI for selecting a time.
Range Slider
A slider UI for picking a min–max range by dragging.
Color Picker
A UI tool for picking a color.
Rich Text Editor
A WYSIWYG editor that supports bold, images, and more.
Truncate
Cutting long text off with "...".
Ellipsis
The "..." mark that signals text has been cut off.
Lazy Loading
Loading only what's visible first and the rest as you scroll.
Infinite Scroll
A UI that keeps loading more content as you scroll.
Pull to Refresh
On mobile, pulling down on the screen to refresh.
Swipe
A mobile gesture of pushing left/right or up/down.
Tab Bar
A key menu bar pinned to the bottom of a mobile screen.
Safe Area
Laying content out so it avoids the iPhone notch and similar obstacles.
Gesture
The full set of finger actions: tap, double tap, long press, pinch, swipe, etc.
Frontend
The part of an app users see (HTML, CSS, JS).
Backend
The server and database logic running behind the scenes.
Full Stack
Working across both the frontend and backend.
Framework
Skeleton code that accelerates development — React, Next.js, and so on.
Library
A collection of prebuilt code for specific functionality.
Component
A reusable unit of UI, like a button or card.
Application Programming Interface
An agreed-upon channel for exchanging data between pieces of software.
Endpoint
A specific URL in an API — sending a request returns data.
Create/Read/Update/Delete
Create, Read, Update, Delete — the four basic data operations an app needs.
Routing
The structure that maps URLs to pages.
State Management
Keeping and sharing data like login status or cart contents across screens.
Database
A storage system for saving and retrieving data.
Schema
The design of a database table — its columns, types, and so on.
Migration
The work of changing the structure of a database.
Object-Relational Mapping
A tool that lets code talk to the database without writing SQL directly.
Authentication / Authorization
Authentication (who you are) and authorization (what you can do).
Token (JWT, etc.)
A credential passed around to keep a user logged in.
Middleware
Logic that sits between a request and its handler.
Environment Variable
Sensitive config like API keys, managed in a .env file.
Boilerplate
The starter template code you use to kick off a project.
Scaffolding
Auto-generating a project skeleton — folders, config files, and more.
Package Manager
A tool for installing and managing libraries — npm, pip, and so on.
Dependency
An external library your project needs in order to work.
Git
A version control system that tracks code changes over time.
Commit
A checkpoint that records a set of code changes.
Branch
An independent copy of the code, branched off from the main line.
Merge
Combining a branch's changes back into the main code.
Pull Request
A request for others to review and merge your code changes.
Refactoring
Cleaning up code structure without changing its behavior.
Software Development Kit
A bundle of dev tools that makes integrating with a service easy.
Quality Assurance
The whole process of verifying that what you built actually works.
Bug
A flaw where something doesn't behave as intended.
Debugging
The process of finding and fixing errors in code.
Error Log
Error messages a program prints — paste them to an AI for faster fixes.
Console
The log panel in browser dev tools where errors show up.
Stack Trace
A step-by-step trail of the code path that led to an error.
Unit Test
A test that checks a single function or component in isolation.
Integration Test
A test that checks whether multiple modules work together correctly.
End-to-End Test
A test that exercises an entire user scenario from start to finish.
Edge Case
An extreme situation like putting emoji in a password.
Happy Path
The ideal scenario where everything works as expected.
Regression
When a new feature breaks something that used to work.
Cross-Browser Testing
Checking behavior across browsers like Chrome and Safari.
Responsive Testing
Verifying that layouts look right across different screen sizes.
Performance Testing
Measuring things like page load speed and server response time.
Load Testing
Checking whether the service holds up under many concurrent users.
Smoke Test
A quick sanity check covering just the core features.
User Acceptance Testing
A test where real users try the service and sign off on it.
Beta Test
Releasing to a limited group before launch to gather feedback.
Hotfix
A quick patch that fixes an urgent bug.
Issue Tracker
A tool for logging and tracking bugs and tasks — Jira, Linear, etc.
Reproduce
Recreating the exact conditions that trigger a bug.
Test Case
A scenario defining "given this input, expect this outcome".
Code Coverage
A metric showing what percentage of the code is exercised by tests.
Mocking
Replacing an external API or DB with a fake for testing.
Lint / Linting
Tools that automatically check code style and catch likely errors.
Code Review
The process of having others read your code and give feedback.
Sandbox
An isolated environment where you can test without touching production.
Fallback
A safety net that provides alternate behavior when something fails.
Error Handling
Handling errors gracefully so the program doesn't crash.
Deploy
Pushing code to a server so it's actually usable.
Hosting
The server space where a web service runs — Vercel, AWS, and others.
Domain
A website address, like example.com.
SSL Certificate
A security certificate that encrypts data for safe communication.
Domain Name System
The system that translates domain names into server IP addresses.
Content Delivery Network
A network that distributes content worldwide to deliver it quickly.
Continuous Integration/Deployment
A pipeline that automatically tests and deploys code when you push it.
Staging
A private test environment that mirrors production.
Production
The real, live environment that actual users connect to.
Rollback
Reverting to a previous version when something goes wrong.
Downtime
Time during which the service is unavailable.
Monitoring
Watching the service in real time — error rate, response time, and so on.
Logging
Recording what the service does — essential for tracing problems later.
Alert
A system that sends notifications when errors happen — via Slack, email, etc.
Scaling
Increasing server resources to handle a growing user base.
Auto Scaling
Servers automatically scaling up and down based on traffic.
Load Balancer
A device that spreads traffic across multiple servers.
Container (Docker)
Tech that bundles an app with its runtime so it runs the same everywhere.
Serverless
A model where you just deploy code and the platform runs it for you.
Caching
Storing frequently requested data to respond faster.
Environment Separation
Running development, staging, and production as separate environments.
Blue-Green Deployment
Running the old (blue) and new (green) versions side by side and switching between them.
Canary Deployment
Rolling a new version out to a small slice of users first to validate it.
Search Engine Optimization
Optimizing a site so it shows up well in search engines.
Analytics
Tools for analyzing visitor counts and behavior — GA4, among others.
Service Level Agreement
A commitment to guarantees like uptime and response time.
Backup
Copying data and systems and keeping them safe.
Disaster Recovery
The plan and procedures for restoring a service after an outage.
Launch Checklist
A list of items to check before deploy — SSL, SEO, error handling, and more.
Postmortem
A document written after an incident, capturing the cause and how to prevent recurrence.
Prompt Engineering
The craft of designing and refining prompts to get the result you want from an LLM.
Context Engineering
Designing what information to put into an LLM's context window and in what order.
Harness Engineering
Designing the scaffolding (tools, loops, checks) around an agent so it doesn't fall off the rails.
System Prompt
A higher-priority instruction that sets the model's role and rules above any user message.
Few-Shot Prompting
Showing the model a few examples in the prompt so it follows the pattern when answering.
Chain of Thought (CoT)
Letting a model write out its reasoning step by step to improve answer quality.
Prompt Injection
An attack where hidden instructions in user input hijack the model's original directives.
Context Window
The maximum amount of tokens a model can read at once.
Prompt Caching
Reusing a long system prompt across calls to cut cost and latency.
LLM Token
The smallest unit of text an LLM processes — usually a sub-word piece.
AI Agent
An LLM system that calls tools and decides next actions on its own to reach a goal.
Agent Loop
The observe → think → act cycle an agent repeats to make progress on a task.
Multi-Agent
A setup where multiple agents collaborate by splitting roles.
Subagent
A helper agent the main agent spawns to handle a specific subtask.
Model Context Protocol (MCP)
A standard protocol for connecting LLM clients to external tools and data.
Tool Use / Function Calling
An LLM selecting and invoking pre-declared functions to act on the world.
Human in the Loop (HITL)
A design that intentionally inserts human approval or correction at risky or critical steps.
Guardrails
Safety checks placed around model inputs and outputs to keep behavior within policy.
Evals
A benchmark dataset used to measure an LLM system's performance automatically and repeatedly.
Retrieval-Augmented Generation (RAG)
A pattern where the model retrieves external documents and answers using them as context.
Vibe Coding
A workflow where you build software by talking intent to an LLM instead of writing code yourself.
Claude Code
Anthropic's terminal-based coding agent CLI.
Cursor
A VS Code-based editor with AI chat and inline editing built in.
GitHub Copilot
GitHub and OpenAI's IDE code completion and chat assistant.
Vercel v0
Vercel's AI tool that generates React/Tailwind UI from a prompt.
Lovable
A no-code AI builder that generates and deploys full-stack web apps from a prompt.
Bolt.new
StackBlitz's in-browser AI builder that spins up full-stack apps on the fly.
Replit Agent
A coding agent inside Replit that builds and deploys apps for you.
Windsurf
Codeium's agent-first AI code editor.
opencode
An open-source terminal coding agent inspired by Claude Code.
Large Language Model (LLM)
A large neural network trained on huge text corpora that can perform many language tasks.
Fine-tuning
Further training a pre-trained model on domain data to specialize it.
Reasoning Model
An LLM trained to spend extra internal 'thinking' before answering.
Multimodal
A model that handles images, audio, or video alongside text.
Embedding
A numeric vector representation of text or images that captures meaning.
Hallucination
When a model fabricates plausible-sounding but false information.
Model Distillation
Transferring a large model's knowledge into a smaller one to gain speed and cost savings.
Model Card
A one-page document summarizing a model's purpose, limits, and evaluation results.
Vector Database
A database built to store and search embedding vectors.
Streaming Response
Sending LLM output token by token so the UI can show it as it generates.
React Server Components (RSC)
React components rendered on the server that can read data directly.
Edge Function
A short server function that runs on global edge nodes close to users.
Monorepo
Keeping many projects together in a single repository.
Feature Flag
A config switch that turns features on or off without redeploying code.
Observability
The ability to infer a system's inner state from outside via logs, metrics, and traces.
SSR / SSG / ISR
Three rendering strategies: per-request, at build time, and incrementally regenerated.
WebSocket
A protocol that opens a single persistent connection for real-time two-way messaging.
WebAssembly (WASM)
A binary format that runs in the browser at near-native speed.
GitOps
An ops style where Git is the single source of truth and infra is auto-synced from it.
Chaos Engineering
Deliberately injecting failures to verify a system's resilience.
OpenClaw
An open-source AI agent that runs locally and uses messaging apps (Signal, Telegram, etc.) as its UI.