Web App Terminology

Explore Web App Terminology: Web basics and Formats and languages.

Web App Terminology

A quick reference for terms you’ll see while learning modern web apps and Wappler. This is here so you don’t have to guess what something means.

TIP: Skim when you want. Most people get more value from this after they’ve seen the concepts once.

Request → response

The web
loop

JSON

Most APIs
return data

Wappler mapping

App Connect
+ Server Connect

Use this as a reference while learning (not a test to memorize).

Skim the spotlight lines first, then use the tables for details.

If a term feels fuzzy, jump back to the matching basics tour.

Web basics

If you remember only one thing: the browser sends requests, the server returns responses. Wappler’s tools map onto that same flow.

Browser

Runs UI
JS/HTML/CSS

Server

Runs logic
returns data

Request

URL + method
payload

Response

HTML/JSON
status

Everything is request → response, even ‘simple’ pages.

The server is the safe boundary for data + permissions.

APIs are just named request/response contracts.

Term	What it means	Why you care
Web app	A browser-based app that loads UI and talks to a server.	Wappler builds real web apps: UI + server workflows.
Browser	The app on your device (Chrome/Edge/Safari) that runs HTML/CSS/JS.	App Connect runs here.
Server	A program that receives requests and returns responses.	Server Connect runs here.
Request / Response	A message sent to the server, and the server’s reply.	Every page load and API call is this pattern.
HTTP	The protocol used for requests/responses on the web.	App Connect calls Server Connect over HTTP.

Formats and languages

Think of these as layers: HTML is the structure, CSS is the look, JS is behavior, and JSON is how servers usually send data back.

HTML + CSS

Structure +
styling

JS + JSON

Behavior +
data

HTML/CSS = what the UI is and how it looks.

JS = what the UI does.

JSON = what APIs usually return to the UI.

Term	What it means	Typical use
HTML	Page structure (elements).	Layout, components, content.
CSS	Visual styling.	Spacing, colors, responsive layout.
JavaScript (JS)	Behavior and logic in the browser.	UI interactivity, small client logic.
JSON	A text format for structured data (objects/arrays).	APIs commonly return JSON.
API	A defined way to request data/actions from a server.	Your Server Connect actions act like APIs.
Bootstrap	A CSS framework (plus optional JS) for responsive layout and common UI components.	Grid/layout, spacing utilities, buttons, navbars, forms.

Rendering terms

Rendering is simply ‘turning data into what the user sees’. SSR/CSR describes where that rendering happens and what the server returns.

NOTE: Most real apps mix SSR and CSR depending on the page.

SSR

Server returns
HTML

CSR

Browser renders
from data

Hydration

SSR HTML
becomes interactive

SSR returns HTML (great first view + SEO).

CSR returns data and renders UI in the browser.

Most apps mix both depending on the page.

Term	What it means	Example
Rendering	Turning data into visible UI.	Showing a list of products.
SSR (Server-Side Rendering)	Server returns ready-to-view HTML.	Fast first paint, SEO-friendly pages.
CSR (Client-Side Rendering)	Browser builds UI after loading JS and data.	Very interactive apps (dashboards).
Hydration	SSR HTML becomes interactive when JS attaches.	Click handlers start working.

Data terms

Databases are where the ‘source of truth’ lives. Server Connect queries that source, and App Connect shows the results in the UI.

Database

Stores records
reliably

Table

Rows +
columns

Query

Ask for
rows

The database is the source of truth.

Server Connect queries and shapes data safely.

App Connect renders the results in the UI.

Term	What it means	Typical use
Database	A system for storing and querying data.	Users, orders, content, logs.
Table	A collection of records of the same type.	`users`, `orders`, `products`.
Record/Row	One item in a table.	One user.
Field/Column	One property of a record.	`email`, `status`.
Reference	A link between related rows in different tables.	Orders reference customers.
Query	Asking the database for rows that match criteria.	Get the latest orders.

Git + version control terms

Version control is how you track changes over time and collaborate safely. Wappler works with real files, so Git (or SVN) fits naturally.

NOTE: You don’t need Git to start learning. But once you build real projects, version control becomes a superpower.

Commit

A safe
checkpoint

Branch

Try changes
safely

Push/Pull

Sync with
a remote

Version control = track history and undo mistakes.

Commits are snapshots you can return to.

Branches let you work without breaking main.

Term	What it means	Why you care
Version control	A system that records changes to files over time.	Undo mistakes, see history, collaborate.
Repository (repo)	A project folder tracked by version control.	Your Wappler project can be a repo.
Commit	A saved snapshot of changes with a message.	A safe checkpoint you can return to.
Diff	The actual changes between versions.	Review what changed before sharing.
Branch	A separate line of work.	Try features without breaking main.
Merge	Combine changes from one branch into another.	Bring a feature back into main.
Remote	A copy of the repo on a server (GitHub/GitLab/etc.).	Backup + collaboration.
Push / Pull	Send commits to remote / get commits from remote.	Sync with your team or devices.
Conflict	When two changes touch the same lines and Git needs help.	Happens sometimes; you resolve intentionally.

Conclusion

If these terms feel less abstract than before, you’re on the right track. Next, jump into the Wappler UI overview to see where these concepts live in the app.

You have

A reference
you can reuse

Wappler UI
orientation

Goal

Words match
what you saw

Use the glossary as a reference, not a prerequisite.

If a term is unclear, jump back to the related basics tour.

Next: see where these concepts live in the Wappler UI.

Continue

Continue to the Wappler UI overview tour.