How HTML changes the background color or background image with Onmouseover,onmouseout

1. Use onmouseout onmouseover to transform between images:

<image src= "IMG1" onmouseover= "this.src= ' Img2 '" onmouseout= "this.src= ' img1 '" >

2.onmouseover onmouseout Change text background color:

<div width= "height=" onmouseover= "style.backgroundcolor= ' #fff '"

onmouseout= "style.backgroundcolor= ' #bbb '" bgcolor= "#bbb" > Text </div>

3..onmouseover onmouseout Text change background:

<div width= "height=" onmouseover= "this.background= ' 1.gif '"

onmouseout= "this.background= ' 2.gif '" background= "2.gif" > Text </div>

How HTML changes the background color or background image with Onmouseover,onmouseout