Event bubbling refers to a specific way of event propagation in HTML DOM API. This happens when an event occurs within an element inside of another element and when both elements have a handle registered for the said event. When it comes to bubbling, the event which is first captured by the innermost element is eventually relayed to the outer elements.
Once the execution begins from one event, it goes out to the parent element. After that, the execution passes on to the parent element and this continues till the body element.