Hi everyone 👋
Here is something that sounds impossible but happens billions of times a second.
The email you sent this morning never travelled as a single message. Neither did this post. Neither did the last video call you were on.
Every one of them was torn into small pieces first.
Those pieces, called packets, were each stamped with an address, sent out individually (often by completely different routes through different cities and even different countries), and then reassembled at the destination into something that looked exactly like the original. All in a fraction of a second. All completely invisibly.
This is the single most important mechanism in all of networking. And once it clicks, almost everything else in the field starts to make sense.
So in Post 2 of my Networking Foundations series, I set out to make it click, using something everyone already understands: the postal service.
Here is the core idea.
Imagine posting a 500-page manuscript. You cannot fit it in one envelope, so you split it into 500 numbered pages, put each in its own envelope, and post them all. They travel by different routes, arrive out of order, and get sorted back into sequence on arrival using their page numbers.
That is exactly how data moves across a network. The manuscript is your email. The envelopes are packets. The sorting offices are routers.
From that one analogy, the post builds up every core concept:
→ What is actually inside a packet (header, payload, and trailer)
→ Encapsulation, the nested-envelope structure that wraps your data in layers
→ How routers move packets without any single one knowing the full route
→ How TTL stops packets from looping around the internet forever
→ How TCP uses sequence numbers and acknowledgements to recover lost packets and reorder them, turning an unreliable system into one that feels perfectly reliable
And then the part that matters most for anyone thinking about security.
A large amount of network traffic does not travel as a sealed letter. It travels as a postcard. The address has to be visible for routing to work, but on a postcard, so is the message. Anyone positioned along the route, on the same Wi-Fi, the same office network, the same coffee shop hotspot, can potentially read it using free, widely available tools.
This is why the difference between http and https is not a technicality. It is the difference between a postcard and a sealed envelope. On public Wi-Fi especially, it is the difference between your data being private and your data being readable by anyone nearby with five minutes and a laptop.
The post includes six original diagrams built specifically for it, including a full breakdown of packet anatomy, the encapsulation layers, and a side-by-side of what a packet sniffer sees with http versus https.
It is written for a mixed audience. Whether you are completely new to networking, a developer filling in the gaps, or someone studying towards a certification, it is built to meet you where you are.
📦 Read Post 2 here: https://vickkykruzprogramming.dev/blog/how-data-actually-travels-packets-protocols-and-the-postal-service-analogy
This is part of an ongoing 14-post series taking readers from the very basics of networking through to Zero Trust security. Subscribe to our newsletter to get each new post delivered as it publishes. 🔔