Event bubbling

Event bubbling: when an event occurs on an element, the process of the event being passed up to that element's topmost parent

In the HTML structure, it means an event that occurs on a child element affects the parent elements above it.

It's the exact opposite of event capturing (the event being passed from the topmost parent down to the element where the event occurred).

When you want to block event bubbling or capturing, calling e.stopPropagation stops the event from propagating so that only that event runs.

Summary: event bubbling is the event being passed up to the topmost parent when an event occurs on a child element, and the opposite term is event capturing.