Computer Atlas

The Web from Top to Bottom

For intermediates 13 topics (10 required · 3 optional) · updated 2026-06-07

Trace a single HTTPS request from the browser down through HTTP, TLS, TCP, UDP, IP, packets, and routing — the whole stack in one walk.

Reading time
~49 min (+16 min optional)
Level mix
8 beginner · 5 intermediate

This is the counterpart to “Internet from the Bottom Up” — same stack, traversed the other direction. You start at the browser, see what HTTP and HTTPS actually do, drop into the transport layer, then the network layer, then the naming system that knits it all together.

The point isn’t to memorise the layers; it’s to internalise that a browser tab opening a page is dozens of named protocols coordinating, and to know which layer to look at when something breaks.

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Roadmap

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  1. Application

  2. Web Browser

    A program that fetches web pages over HTTP, parses HTML/CSS/JavaScript, and renders them as the interactive sites you see.

  3. HTTP

    The request/response protocol that powers the web — how browsers and servers talk to each other.

  4. REST APIOptional

    An architectural style for HTTP-based APIs that models the world as named resources accessed via standard verbs — the dominant way services talk to each other on the web.

  5. Encryption

  6. HTTPS

    HTTP wrapped in TLS — the encrypted, authenticated version of the web's core protocol, now the default for every public site.

  7. TLS

    The protocol that encrypts and authenticates almost all secure traffic on the internet — the "S" in HTTPS, IMAPS, SMTPS, and many more.

  8. Public-Key CryptographyOptional

    Cryptography using a pair of mathematically linked keys — one you share, one you keep secret. The basis of TLS, signatures, and modern authentication.

  9. Transport

  10. TCP

    A reliable, ordered, stream-based transport protocol on top of IP. The plumbing under most internet traffic.

  11. UDP

    A connectionless, "fire and forget" transport protocol. Faster than TCP but with no delivery, ordering, or reliability guarantees.

  12. Internet

  13. IP Address

    A numeric identifier for a network interface — how computers find each other on the internet.

  14. Packet

    A small, self-describing chunk of data that travels across a network. The internet's fundamental unit of communication.

  15. Router

    A device that forwards IP packets between networks, deciding which neighbour gets each packet on its way to the destination.

  16. Naming

  17. DNS

    The phone book of the internet — translates human-readable names like example.com into IP addresses.

  18. The big picture

  19. OSI ModelOptional

    A seven-layer conceptual model for how networking protocols stack on top of each other — physical wires at the bottom, applications at the top.