What web development is
Key takeaways Web development is building the software that runs on the web. It splits into a front end — the part that runs in your browser and that you see and click — and a back end — the part that runs on a server you never see and that stores data and enforces rules. Someone who works across both is full-stack. Underneath every page is one simple rhythm: the browser sends a request and a server sends back a response. This lesson draws the map; the rest of the module fills it in.
The web is where most software meets its users. When you check a bank balance, book a flight, or watch a scanner dashboard update in real time, you are using a web application — and someone built it. This module is a working developer’s tour of how that gets done. It is not a tutorial for one framework; it is the set of durable ideas that outlast any framework, starting here with the plainest question of all: what is web development?
The front end and the back end
Every web app has two halves, and almost everything in web development hangs off the difference between them.
The front end is the part that lives in your browser. It is the page you look at — the text, images, buttons, forms, and animations — and the code that makes them respond when you click or type. Front-end work is built from three languages you’ll meet soon: HTML for structure, CSS for appearance, and JavaScript for behaviour. Because it runs on the user’s own device, the front end is sometimes called the client side.
The back end is the part the user never sees. It runs on a server — a computer, usually in a data centre, that waits for requests and answers them. The back end holds the data (your account, your saved items, everyone else’s too), enforces the rules (who is allowed to do what), and does the work that can’t safely happen on a stranger’s device. It’s written in languages like Go, Python, JavaScript, Ruby, or Java, and it talks to a database behind it.
A developer who works on the browser side is a front-end developer; one who works on the server side is a back-end developer; and one comfortable across both is full-stack. These are roles and emphases, not walls — the ideas in this module are worth knowing wherever you sit.
Client and server
The reason for the split is a single, load-bearing idea: the web is a conversation between a client and a server.
- The client is the program making the request — almost always a browser, but it could be a mobile app or a script.
- The server is the program that receives the request and sends back a response.
You ask; it answers. That request-and-response rhythm is the heartbeat of the whole web, and we give it a lesson of its own in the client-server web. For now, hold onto the shape: the front end is the client, the back end is the server, and everything that happens between them is one side asking and the other answering.
What happens when you visit a page
Put the pieces together by following one ordinary action — typing an address and hitting Enter. In the second or two before the page appears, a surprising amount happens:
- The browser figures out which server the address belongs to and opens a connection to it.
- It sends a request for the page.
- The server runs its back-end code — perhaps looking things up in a database — and sends back a response: the HTML for the page, plus its CSS and JavaScript.
- The browser renders that HTML and CSS into the visual page, and runs the JavaScript to make it interactive.
- As you click around, the front end may send more requests in the background for fresh data, updating the page without a full reload.
Every step there is a lesson later in this module. How the browser works unpacks step 4; the plumbing of steps 1–3 is the domain of the networking module, especially how a web request works and HTTP, the protocol the request and response are written in.
A spectrum, not a single thing
“A website” and “a web app” sit at different points on one spectrum. At the simple end, a page can be a plain static file the server hands over unchanged — this very learning site is built that way. At the rich end, a page is assembled dynamically for each visitor, with logins, live data, and a database doing real work behind it. Most of what you use daily lives somewhere in between.
The good news is that the same core ideas carry across the whole range. A static page and a sprawling web app both come down to a client requesting and a server responding; they differ in how much happens on each side, not in the shape of the conversation. We map that spectrum directly in static vs. dynamic sites.
Quick check: which part of a web app runs on a server the user never directly sees?
Recap
- Web development is building the software that runs on the web, from a single page to a full application.
- The front end runs in the browser (the client) and is what the user sees and interacts with; the back end runs on a server and holds the data and rules.
- A full-stack developer works across both; the roles are emphases, not walls.
- The web’s underlying rhythm is request and response — the client asks, the server answers.
- Visiting a page sets off a chain: resolve the server, send a request, run back-end code, return a response, and render it in the browser.
- Sites range from static files to dynamic apps, but the same client-server ideas carry across the whole spectrum.
Next up: How the browser works.
Frequently asked questions
What is the difference between front end and back end?
The front end is everything that runs in the browser and that a user sees and touches — the HTML, CSS, and JavaScript that make up the page. The back end is the code that runs on a server the user never sees: it stores data, enforces rules, and answers requests. A full-stack developer works across both.
Do I need to know how to code to understand web development?
No. This lesson and the next few build the mental model with no code at all. You’ll meet HTML, CSS, and JavaScript later in the module, but the ideas — client and server, request and response, front end and back end — come first and stand on their own.
Is web development the same as building a website?
A simple website is one point on a wide spectrum. Web development ranges from a single static page served as a file, up to a full web app with logins, live data, and a database behind it. The tools and ideas scale across that whole range, which is why one module can cover both.