The internet and the world wide web
The internet and the web
- People mix these up, but they're different.
- The internet is the network; the web is something you use on it.
- We'll follow a web page from a typed URL to your screen.
Internet, web, URL and browser
- The internet is the worldwide infrastructure — computers, cables and routers.
- The world wide web (WWW) is the collection of websites you view over the internet (email is another internet service).
- A URL is a page's text address, in three parts: protocol · domain name · path (
https://www.example.com/index.html). - A web browser fetches pages and renders their HTML into what you see.
Practice
What is the difference between the internet and the world wide web?
The internet is the worldwide infrastructure; the WWW is one service (websites) running on it.
Practice
In https://www.example.com/index.html, what are the three parts of the URL?
https is the protocol, www.example.com the domain name, /index.html the path.
Practice
A web browser's job is to:
The browser fetches the HTML and renders it into the page you see.
How a web page reaches you
- The browser needs the site's IP address, but a URL is a name.
- It asks a DNS (domain name service), which stores the IP for each web address.
- The DNS returns the matching IP address.
- The browser contacts the web server at that IP.
- The server sends back the page's HTML, which the browser renders.
Practice
The domain name service (DNS) is used to:
DNS turns the human-readable domain name into the numeric IP address the browser needs.
Cookies
- A cookie is a small text file a website stores on your device to remember things.
- A session cookie is deleted when you close the browser (e.g. a shopping basket).
- A persistent cookie is saved on the device, remembering you between visits (logins, preferences).
Practice
A persistent cookie differs from a session cookie because it:
Persistent cookies stay on the device (logins, preferences); session cookies are deleted on close.
You've got it
Key idea
- the internet = the network; the WWW = websites you use on it
- a URL = protocol + domain name + path; a browser renders HTML
- DNS turns a domain name into an IP address, then the browser fetches the page from the web server
- session cookies vanish on close; persistent cookies are saved for next time