What is event.target ?

In simplest terms, the event.target is the element on which the event occurred or the element that triggered the event.

Sample HTML Markup.

<div onclick="clickFunc(event)" style="text-align: center;margin:15px;
border:1px solid red;border-radius:3px;">
    <div style="margin: 25px; border:1px solid royalblue;border-radius:3px;">
        <div style="margin:25px;border:1px solid skyblue;border-radius:3px;">
          <button style="margin:10px">
             Button
          </button>
        </div>
    </div>
  </div>

Sample JavaScript.

 function clickFunc(event) {
  console.log(event.target);
}

If you click the button it will log the button markup even though we attach the event on the outermost div it will always log the button so we can conclude that the event.target is the element that triggered the event.