Why write e.preventDefault()?

Question

JavaScript

Wrote code for dragging an element from one div to another , but didn't understand why write e.preventDefault() (wrote from the tutorial).
Here are the lines of code with e.preventDefault():

function dragOver(e){
    e.preventDefault(); 
}

Here's another:

function dragEnter(e){
    e.preventDefault();
    this.className += ' hovered'; 
}

Here is what hovered does in CSS:

{
    background: #f4f4f4;
    border-style: dashed;
    background-color: salmon;
}

You need to understand why write e.preventDefault() in these functions
Thanks in advance!

Answer 1

Event.preventDefault()