Module 4: Key Web Concepts

Module objective

Understand the essential technical terms you'll hear often — API, server, database, HTTP, hosting — explained in plain language.

Simple explanation

Technical vocabulary can seem intimidating. But behind every term is a simple concept. Let's go through them one by one.

The server

We've already mentioned it: a server is a computer that's always on and whose job is to respond to requests. When you open a website, it's a server that sends you the page.

Why is it called a "server"? Because it serves web pages, just like a waiter in a restaurant serves dishes.

There's also the word client: that's your browser, the one that requests the page. The web works on this client-server model: one asks, the other answers.

The database

A database is a giant digital filing cabinet where all of a website's information is stored:

• User accounts (name, email, encrypted password)
• Products in a shop (name, price, description, stock)
• Messages on a social network
• Past orders

graph TD
    A["User clicks on 'My orders'"] --> B["The frontend sends the request"]
    B --> C["The backend receives the request"]
    C --> D["It queries the database"]
    D --> E["The database returns the data"]
    E --> F["The backend formats it"]
    F --> G["The frontend displays it"]

Without a database, a website couldn't remember anything. Every visit would be like it had never seen you before.

HTTP and HTTPS

HTTP (HyperText Transfer Protocol) is the language that your browser and the server speak to understand each other. It's the protocol — the set of rules — that defines how requests and responses are formatted.

When you see HTTPS (with an S at the end), the S stands for Secure: the conversation between your browser and the server is encrypted. No one can read what's being exchanged along the way. This is essential for online payments, passwords, and really for all websites today.

How to spot HTTPS? The small padlock in your browser's address bar.

The API

API (Application Programming Interface) is a word that sounds scary, but the concept is simple. An API is a standardized counter that allows two pieces of software to communicate with each other.

Imagine your phone's weather app shows the temperature. It doesn't measure the temperature itself — it asks for the information from a weather service through its API. The API says: "If you give me a city name, I'll send you the temperature."

APIs are everywhere:

Hosting

Hosting a website means storing it on a server so that it's accessible to everyone, 24/7. A website that isn't hosted is like a book that isn't in any library: it exists, but no one can access it.

Hosting providers are companies that own thousands of servers and rent you space on them:

The domain name

The domain name is the human-readable address of your website: www.mysite.com. In reality, computers communicate using numbers (IP addresses, like 142.250.74.238). The domain name is an alias that translates an easy-to-remember name into a number that machines understand.

It's like your phone's contacts: you search for "Mom" instead of dialing 555-123-4567 every time.

The system that handles this translation is called DNS (Domain Name System) — the phone book of the web.

graph LR
    A["You type www.google.com"] --> B["DNS translates it to 142.250.74.238"]
    B --> C["Your browser contacts the server at that address"]
    C --> D["The server sends back the page"]

Cookies

Cookies are small files that websites store on your computer to remember you. When a website says "We use cookies," here's what that actually means:

• Session cookie: remembers that you're logged in (without it, you'd have to re-enter your password with every click)
• Preference cookie: remembers your choices (language, dark theme...)
• Tracking cookie: follows your browsing to show you targeted ads

The first two are useful. The third one is the one that sparks the privacy debate.

Concrete example

You order a pizza online:

1. You open the website (your browser is the client)
2. The page loads (the server sends the frontend via HTTP)
3. You log in (the backend checks the database)
4. You choose a pizza and click "Order" (JavaScript sends the order to the backend)
5. The site displays a map for delivery (Google Maps API)
6. You pay (Stripe API for secure payment via HTTPS)
7. The order is saved (database)
8. The site sets a cookie to remember your address next time

Every concept from this module comes into play in this simple everyday action.

Metaphor

Think of the web as an ultra-fast postal service:

• The server is the post office that processes your mail
• The database is the archive where all records are kept
• HTTP is the official language in which letters are written
• HTTPS is the same letter, but in a sealed envelope that only the recipient can open
• The API is the standardized form you fill out to make a request — it ensures everyone uses the same format
• The domain name is the simple address written on the envelope, and DNS is the directory that translates that address into GPS coordinates
• Cookies are sticky notes that the post office attaches to your mailbox to remember your preferences

Summary in 3 key points

1. The web relies on a client-server model: your browser asks, the server answers, and the database stores the information
2. APIs allow software to communicate with each other — they are the invisible glue that connects web services
3. HTTPS, DNS, and cookies are the mechanisms that make your browsing secure, readable, and personalized