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Beginner · Lessons: 4

How the internet works

What really happens between your computer and a website, who takes part, and what each of them can see.

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  1. 1 What happens when you open a website

    Follow one click from your Mac to a website and back, and see who is involved along the way.

    7 min
  2. 2 Packets, routers and the path your data takes

    What actually happens to your data between your Mac and a server: chopped into packets, passed hop by hop, sometimes under an ocean.

    7 min
  3. 3 HTTPS and certificates: what the padlock proves and what it doesn’t

    What TLS actually does, what a certificate really certifies, and why the padlock is not a verdict on whether a site is trustworthy.

    8 min
  4. 4 VPNs, Tor and proxies: who you shift trust to

    A VPN, Tor and a proxy each hide different things from different people. None of them make you invisible, and each asks you to trust someone.

    8 min

Free, no account, nothing tracked. Your progress stays in this browser.