So far in this series we’ve looked at the parts of the Go runtime that orchestrate execution — the memory allocator, the scheduler, the garbage collector, sysmon, the netpoller. Today we’re switching gears and looking at three of the most ordinary things in Go: slices, maps, and channels. They are the bread and butter of every Go program. You probably write all three of them several times before lunch. But “ordinary” is doing a lot of work in that sentence. None of these are language primitives in the way an int is — they all have real, non-trivial data structures behind them, allocated on the heap, managed by the runtime, and tuned aggressively for performance. The syntax (s[i], m[k], <-ch) hides all of that, and that’s the point. But once you peel the syntax back, what’s actually sitting in memory? That’s the question we’re going to answer.