Macrotasks (or tasks) are fundamental to JavaScript's event loop: 1) Include setTimeout, setInterval, setImmediate, I/O, and UI rendering, 2) Execute one at a time after microtasks are completed, 3) Represent the main unit of work in the event loop, 4) Are processed in the order they were scheduled, 5) Allow for UI updates and rendering between tasks, 6) Help prevent long-running operations from blocking the main thread.