JavaScript employs the Event Loop in the browser to process asynchronous operations. It consists of: Call Stack Web APIs and Callback Queue When an asynchronous operation is completed, it places its callback in a queue known as the 'callback queue'. The Event Loop continually monitors the call stack and the call back queue. When a callback is clear, the event loop picks a callback from the queue and pushes it onto the stack for execution. The call stack records function calls in a Last-In-First-Out (LIFO) manner. Function calls push onto the stack: every time a function is invoked a stack frame is created and pushed onto the call stack Function returns pop the stack: when a function execution completes, its stack frame is popped from the stack. Thus, at any given point, only one stack frame (function) is actively executing, adhering to the principle of single-thread execution.