Terminology: Frontend vs Backend

Web development has a lot of concepts and technologies that are essential for building, deploying, and maintaining modern websites. Below are some key terms, explained in the context of frontend and backend development.

Keep in mind that this list is not exhaustive there are way more terms, these are just the ones I believe to be more crucial to understand.

What is the Frontend?

The frontend refers to everything you as a user interact with in a web or mobile application, the everything you see your browser or on the apps you've installed on your device. Frontend development focuses on what the user will see (UI), interactivity, and user experience (UX).

HTML HyperText Markup Language:

Hold's Information of the structure of webpage's, by defining elements like headings, paragraphs, links, images, tables and forms.

Web Browser's read html and convert it to the visuals we see when we go to any website.

CSS Cascading Style Sheets:

Contains Instructions on the style of HTML web page and elements including colors, fonts, spacing, and layout.

DOM Document Object Model

A tree-like in-memory representation of a webpage that JavaScript can access and manipulate to update content dynamically.

SPA Single Page Application

A web app that loads one HTML page and dynamically updates content without full page reloads (e.g., React, Angular, Vue apps).

SSR Server-Side Rendering

The server generates the full HTML page for each request, improving SEO and initial load time.

CSR Client-Side Rendering

The browser downloads a minimal HTML shell and JavaScript builds the page dynamically in the client.

Hydration

The process of attaching JavaScript event listeners to server-rendered HTML to make it interactive on the client.

Bundler

A tool (like Webpack, Vite, or esbuild) that combines many JavaScript/CSS files into optimized bundles for the browser.

Responsive Design

Design approach ensuring a UI adapts gracefully to different screen sizes using CSS media queries or utility frameworks like Tailwind CSS.

API Call

A request from the frontend to the backend (typically via HTTP/REST or GraphQL) to fetch or send data.

What is the Backend?

The backend refers to the server-side of an application the logic, data, and infrastructure that users do not see directly. It handles requests from the frontend, processes business logic, computes calculations that are complex and resource intensive, communicates with databases, and returns responses.

Server

A machine or process that listens for and responds to client requests. Can be physical hardware or cloud-hosted (AWS, GCP, Azure).

API Application Programming Interface

A solution defines how the frontend communicates with the backend, typically via REST, GraphQL, or gRPC.

REST Representational State Transfer

an architectural style for APIs using HTTP methods (GET, POST, PUT, DELETE) to manage resources.

GraphQL

A query language for APIs that allows clients to request exactly the data they need, reducing over-fetching and under-fetching.

Database

A system for persistently storing and querying data. Can be relational (SQL) or non-relational (NoSQL) like MongoDB, PostgreSQL, or Redis.

ORM Object Relational Mapper

A library that lets developers interact with a database using their programming language instead of raw SQL.

Middleware

Functions in a backend framework that process requests before they reach the final handler (e.g., authentication checks, request logging, CORS handling).

Authentication

The process of verifying who a user is (e.g., username/password, OAuth, JWT tokens).

Authorization

The process of determining what an authenticated user is allowed to do (e.g., role-based access control).

Microservices

An architectural pattern where a backend is composed of small, independently deployable services instead of one large monolithic application.

Containerization

Packaging an application and its dependencies into a container (e.g., Docker) so it runs consistently across environments.

WebSocket

A protocol enabling real-time, bidirectional communication between a browser and server — used in chat apps, live dashboards, and gaming.