The wrong mental model
For a long time I pictured a packet as a thing. A little sealed capsule that leaves my laptop, hops from router to router, and arrives at a server on the other side of the planet — the same object the whole way, like a parcel with my address on it.
That picture is wrong. Not slightly wrong. Structurally wrong.
Start at the top
When my browser sends an HTTP request, that request is just data. The layers below it exist to move that data, and each one wraps it in its own header.
