The Internet and Its Uses
Internet vs WWW, HTTP/HTTPS, DNS, web browsers, cookies, digital currency, and cyber security.
1 Internet vs World Wide Web
- The global physical infrastructure
- A network of networks — cables, routers, servers
- Carries all internet traffic (email, streaming, web, VoIP)
- Exists independently of the web
- A collection of websites and web pages
- Accessed using the internet via a browser
- Uses HTTP/HTTPS protocols
- One service that runs on top of the internet
The Internet and the World Wide Web are not the same thing. The internet is the infrastructure; the web is one service that uses it.
2 URLs
A URL (Uniform Resource Locator) is a text-based address that uniquely identifies a web page or resource on the internet.
https://painlessprogramming.com/understanding-number-systems/ │ │ │ │ │ └── Web page / file path │ └──────────────────────── Domain name └──────────────────────────────── Protocol (HTTPS)
A URL can contain: the protocol, the domain name, and the file path. Domain names are resolved to IP addresses by DNS servers.
3 HTTP & HTTPS
| HTTP | HTTPS | |
|---|---|---|
| Full name | HyperText Transfer Protocol | HyperText Transfer Protocol Secure |
| Purpose | Transfers web pages between server and browser | Same as HTTP but with encryption |
| Encryption | None — data sent in plain text | Uses SSL/TLS to encrypt data |
| Security | Data can be intercepted and read | Data is encrypted and cannot be read if intercepted |
| Use | Basic web pages with no sensitive data | Online banking, shopping, login pages |
4 Web Browsers
A web browser is an application whose main purpose is to request, receive, and render HTML to display web pages to the user.
Browser Functions
- Storing bookmarks and favourites
- Recording and displaying browsing history
- Allowing multiple tabs to be open simultaneously
- Storing and managing cookies
- Providing navigation tools (back, forward, refresh, home)
- Providing an address bar for entering URLs
5 How Web Pages Load
When a user types a URL and presses Enter:
- The browser extracts the domain name from the URL
- The browser sends the domain name to a DNS (Domain Name Server)
- The DNS looks up the domain and returns the corresponding IP address
- The browser sends an HTTP/HTTPS request to the web server at that IP address
- The web server sends back the requested HTML (and CSS, JS, images)
- The browser renders the HTML and displays the web page to the user
DNS acts like a phone book for the internet — it translates human-readable domain names (e.g. painlessprogramming.com) into machine-readable IP addresses (e.g. 185.230.63.186).
6 Cookies
A cookie is a small text file stored on a user's device by a website. It allows the website to remember information about the user across sessions.
- Temporary — deleted when the browser is closed
- Used for: keeping a user logged in during a visit
- Holding items in an online shopping cart
- Tracking activity within a single session
- Saved on the device for a set period of time
- Used for: remembering login details
- Saving user preferences (language, theme)
- Tracking user behaviour across multiple visits
7 Digital Currency & Blockchain
A digital currency is a form of money that exists only in electronic form — there is no physical equivalent (no coins or notes). Example: Bitcoin.
Blockchain is a digital ledger — a time-stamped, ordered list of transaction records that is distributed across many computers. Each block in the chain contains a set of transactions and a reference to the previous block, making it tamper-evident.
Blockchain's key property: once a record is added, it cannot be altered without changing all subsequent blocks — making fraud very difficult to carry out undetected.
8 Cyber Security Threats
Know the difference: Phishing = fake emails. Pharming = fake websites via DNS manipulation. Social engineering = manipulating people (not systems).