Hot Take: Nothing in computing is truly asynchronous at the hardware and instruction level. Everything is synchronous, until a runtime fakes it. People talk about async like it's a magical property of the universe. But at the lowest level, every system is ultimately synchronous. -CPUs appear to execute instructions in order (even though they reorder internally) -Syscalls block unless the OS schedules around them -Hardware is event-driven but still bound by clocks -“Async” functions don’t run in parallel, the runtime schedules them So what’s actually happening? Async is an illusion built by runtimes: -JavaScript: event loop + callback/microtask queue -Rust: executor + waker + poll-based futures -Python: event loop + coroutines -Go: scheduler multiplexing goroutines over OS threads -OS kernels: interrupts + preemptive scheduling Under the hood, it’s all synchronous execution broken into chunks and interleaved by a scheduler. -Async ≠ “parallel” -Async ≠ “multithreaded” -Async = “scheduled synchronous steps that look concurrent” The runtime just decides when your synchronous fragments run. In summary: Every system is synchronous at its core. Async is a runtime abstraction that slices sync operations into interleaved steps that feel concurrent. It's the core concept of Asynchronous. I am always open to feedbacks, because through your feedback I get to know a lot.