Beginner · 5h 28m · 21 lessons
How the Internet Works
From typing a web address to a page on your screen — demystified, one hop at a time.
What you'll learn
- ✦Explain what a client and a server each do, and say which role each device plays in an exchange
- ✦Explain what an IP address is and why every device on a network needs one
- ✦Trace how DNS turns a name like
example.cominto an IP address, and where caching speeds it up - ✦Break a URL into its parts and say what each one does
- ✦Read an HTTP request and response, and diagnose a problem from its status code
- ✦Explain how data is split into packets and routed, hop by hop, across many networks
- ✦Explain what HTTPS and TLS protect, and what the padlock does and does not promise
- ✦Trace, end to end, how a hosted website reaches a browser on the other side of the world
- ✦Explain how cookies, caching, CDNs and "the cloud" shape the web you use every day
- ✦Spot a phishing message, protect accounts with strong passwords and 2FA, and decide how to limit online tracking
Part of these career paths
- Absolute Beginner path · course 1 of 6
Certification projects
Build 3 projects to earn your certificate
Hands-on work that proves you can apply what you learned — part of the certificate requirements.
Syllabus
Module 1 · 46m
The big picture Free
What you'll be able to do
- Can explain the internet as a network of networks, and tell it apart from the Web and Wi-Fi
- Can say which device is the client and which is the server in any exchange, even when one computer plays both
- Can put the steps of one web request in order, from pressing Enter to seeing the page, and use them to guess where a slow page is stuck
Module 2 · 1h 5m
Names & addresses Locked
What you'll be able to do
- Can explain what an IP address does, check an IPv4 address with the 0 to 255 rule, and tell public from private addresses
- Can explain what DNS does, and why buying a domain isn't the same as having a website
- Can trace a DNS lookup through the cache, the resolver and the name servers, and explain what TTL controls
- Can split a URL into its parts and find the real domain in a look-alike link
Module 3 · 1h 7m
Talking to servers Locked
What you'll be able to do
- Can read a simple HTTP request and response and name each part: method, path, headers, status and body
- Can choose the right HTTP method (GET, POST, PUT or DELETE) for an everyday action
- Can sort any status code into its family and say whose side a problem is on
- Can work out which port a URL uses, and explain what localhost:3000 means
Module 4 · 1h 4m
Delivery & trust Locked
What you'll be able to do
- Can explain why data travels as numbered packets and how routers pass them on, one hop at a time
- Can trace a connection from a home device through the router and ISP, and tell where a fault sits
- Can say what the HTTPS padlock proves and what it doesn't, and find a link's real domain before typing a password
- Can list what a website needs to go live, and work out why visitors can't reach it
Module 5 · 42m
The modern web Locked
What you'll be able to do
- Can explain how a cookie and a session id keep you logged in, and tell first-party from third-party cookies
- Can explain why caches and CDNs make pages load faster, and work out travel time from distance
- Can spot a stale cached page and fix it with a hard refresh
- Can say where cloud data really lives, and work out what renting extra servers for a busy day costs in server-hours
Module 6 · 44m
Safety & privacy Locked
What you'll be able to do
- Can spot a phishing message by its rush and its look-alike address, and explain why a UPI PIN or OTP is never shared
- Can explain why a long, unique password plus 2FA keeps an account safe after a leak
- Can say what incognito, a VPN and blocking third-party cookies each hide, and from whom
- Can act in the first minutes after a scam: change the password, turn on 2FA, report it