I like this version: <a href="https:&#x2F;&#x2F;github.com&#x2F;alex&#x2F;what-happens-when" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;alex&#x2F;what-happens-when</a><p>It doesn&#x27;t address the &#x27;progressive layers&#x27; issue, but it _does_ include a TOC.<p>I have been asked this question before, and my answer was definitely biased towards the networking parts (DNS, TCP&#x2F;IP, HTTP&#x2F;S, certificates ...), and I provided absolutely no detail about keyboard&#x2F;mouse&#x2F;monitor I&#x2F;O, parsing or rendering.