Understanding the Internet in 5 Layers - A Mental Model for Non-Initiates

A ticket that explains the network and the Internet from scratch, without jargon. You get a useful mental model even if you never code a socket.

In plain terms

Internet, it's not a "cloud". It's five layers of conventions that talk to each other, stacked like a sandwich: the physical layer (cables), the link layer (direct neighbors), the IP layer (global addresses), the transport layer (TCP/UDP - deliver without losing), and the application layer (HTTP, e-mail…). Each layer only knows its neighbors.

The affair

The article fazamhd.com/mental-models/networking takes the model taught at Stanford or Berkeley (CS144) and serves it without acronyms. The right image: sending a postcard. You write on the back (application). You put it in an envelope with an address (IP). You drop it in a mailbox (transport). It travels by truck, train, plane (link). On asphalt or rails (physical). Each of these layers is stupid - it just knows how to pass to the neighbor - but stacked, they make the Internet work.

Why is this useful even for a non-dev? Because 90% of the tech debates we read ("net neutrality", "sovereign 5G", "IPv6", "end-to-end encryption", "TCP vs QUIC") are debates about a specific layer - and guess what, we understand nothing until we know which one.

To watch

• The gradual shift from TCP to QUIC (Google, IETF standard since 2021) - faster on mobile, but obscures what access providers see. Political battle underway.
• AI changes the network layer itself little, but explodes the needs of layer 1 (fiber, backbones) - see data centers.