The image is not repeated (and hence the background image painting area will not necessarily been entirely covered). The position of the non-repeated background image is defined by the background-position CSS property.

The image is repeated in the given direction as much as needed to cover the whole background image painting area. The last image may be clipped if the whole thing won't fit in the remaining area.

The image is repeated in the given direction as much as needed to cover most of the background image painting area, without clipping an image. If it doesn't cover exactly the area, the tiles are resized in that direction in order to match it.

The image is repeated in the given direction as much as needed to cover most of the background image painting area, without clipping an image. The remaining non-covered space is spaced out evenly between the images. The first and last images touches the edge of the element. The value of the background-position CSS property is ignored for the concerned direction, except if one single image is greater than the background image painting area, which is the only case where an image can be clipped when the space value is used.