Episodes

Every explainer, in one place.

These are the episodes published so far. Each one follows a single journey through a piece of technology — start anywhere. New explainers are added regularly on YouTube.

Published episodes

17 explainers and counting, across networking, the web, wireless, payments and security.

Networking

What Happens When You Type a URL in the Browser?

In the two seconds it takes to read this, your browser can race across four continents and back — to paint one page.

4:09Watch ▶
DNS

DNS — How the Internet Finds Websites

Type a website's name and press Enter. That name means nothing to the internet — so someone has to translate.

4:32Watch ▶
DNS

DNS Root Servers — the Internet's 13 Names

Thirteen. That's how many root server names hold up the entire internet. Here's what they really do.

5:01Watch ▶
DNS

DNS Load Balancing — Many Answers to One Question

Two people on two continents type the same address at the same second — and get sent to different machines.

5:13Watch ▶
Web · TLS

TLS Handshake — What the Padlock Actually Does

The little padlock is the visible end of a fast, invisible negotiation. Here's the whole handshake.

3:55Watch ▶
Web · Sessions

Cookies on the Wire — How Sessions Travel

Log in once, and for hours you never type your password again. A tiny string is doing the remembering.

5:10Watch ▶
Networking

DHCP — How Your Device Gets Its Address

A fresh device joining a network is a tourist with amnesia: no address, no map, no language for the locals.

3:55Watch ▶
Networking

The OSI Model — Seven Layers of the Internet

Every click doesn't travel straight to the network — it falls through seven layers first. Here they are.

4:14Watch ▶
Transport

TTL — Why Packets Can't Loop Forever

Two routers, each sure the other knows the way, could bounce a packet forever. One number stops them.

4:33Watch ▶
Wi-Fi

How Wi-Fi Gets You Online

The last ten metres of the internet are the strangest: no cables, just invisible radio filling the room.

3:41Watch ▶
Wireless

Radio Waves — How Data Rides the Air

Right now, invisible waves are carrying calls, videos and downloads through open air — no wire in sight.

5:12Watch ▶
Mobile

How a Text Message Travels

Every day, hundreds of billions of messages make this trip. Follow one from your thumb to theirs.

3:17Watch ▶
Payments

What Happens When You Tap "Pay"

You're at a counter. In under a second, a chain of systems approves the money. Here's the chain.

3:41Watch ▶
Security

Honeypots — Traps for Hackers

Most of security is about building walls. A honeypot does the opposite — it invites the attacker in.

5:33Watch ▶
Security

Antivirus — the Original Digital Immune System

Right now a program is reading every file you touch — every download, attachment and USB stick. Why?

5:29Watch ▶
Security · IAM

IAM — Who Gets Into What

Every company app has one quiet question in front of it: should this person open this thing right now?

5:19Watch ▶
Security

Phishing Simulation — Faking the Attack to Teach the Lesson

The best way to understand a risky moment is to follow one — safely, on purpose, before a real one lands.

3:24Watch ▶

Much more on the way

These episodes come from a structured library of 950 topics across 18 subject areas. New explainers are published regularly — the best way to keep up is to follow the channels.