Since css2, we are using background images. But there were some limitation( in css2 ) that only one image can be used for a single element. Another limitation were that background images with background-repeat:no-repeat are for fixed elements only. For liquid elements like body, background images are full only if screen resolution and image size are same. But CSS3 introduced background size property to overcome this issue.
Various Background Properties
|Background-color||color of background|
|Background-image||url or gradient of background image|
|Background-repeat||repeat (default), no-repeat, repeat-x, repeat|
|Background-position|| position of background image, first value for x-axis and second for y-axis,
|Background-size||auto( default), cover, contains Introduced in css3|
|Background-origin||padding-box(default), content-box and border-box Introduced in css3|