minor

2-ui/99-ui-misc/03-event-loop/article.md

@@ -337,3 +337,13 @@ To schedule a new microtask:
 There's no UI or network event handling between microtasks: they run immediately one after another.
 
 So one may want to `queueMicrotask` to execute a function asynchronously, but also with the same application state.
+
+```smart header="Web Workers"
+For long heavy calculations that shouldn't block the event loop, we can use [Web Workers](https://html.spec.whatwg.org/multipage/workers.html).
+
+That's a way to run code in another, parallel thread.
+
+Web Workers can exchange messages with the main process, but they have their own variables, and their own event loop.
+
+Web Workers do not have access to DOM, so they are useful, mainly, for calculations, to use multiplle CPU cores simultaneously.
+```