left and top attributes. Also, you should set position:relative;
on some parent element to make it a layer, so that the absolute
positioning uses that element as origin. If you don't specify the
origin, it may be the window or it may be some other element, and you
don't know where your absolutely positioned element will end up.
There are some other alternatives to place elements on top of each other, each with their own limitations.
You can use relative positioning to make text display on top of an image:
<img src="..." alt="" />
<div style="position:relative;top:-50px;">
This text will display 50 pixels higher than it's original position,
placing it on top of the image. However, the text will still take up
room in it's original position, leaving an empty space below the image.
</div><div>
<div style="float:left;">
This text will be on top of the image. The parent element
gets no height, as it only contains floating elements.
However, IE7 and earlier has a bug that gives the parent
element a height anyway.
</div>
</div>
<img src="..." alt="" />
