How this guide is organised

Every chapter follows the same shape:

   In one sentence      the whole idea, compressed
   Why this matters      the cost/reliability/incident reason to care
                         (useful even if you'll never type the command)
   How it actually works  the mechanism, explained from first principles
   Real-world example     a genuine, named incident or system -- not a
                         toy story
   Try it yourself        hands-on, on your own machine or a free VM
   Common mistakes         where people misunderstand this, and why
   Check yourself          questions (answers in Appendix E)
   Further reading         a book, a doc, a talk -- picked for clarity

Honesty markers, used throughout:

   Simplified:  a true statement that leaves out detail you don't need yet
   Debated:     practitioners genuinely disagree here
   Dangerous:   don't run this outside a throwaway VM/container