http://www.barelyfitz.com/screencast/html-training/css/positioning/
With position:relative, you can use top or bottom, and left or right to move the element relative to where it would normally occur in the document.
If we set relative positioning on a div, any elements within this div will be positioned relative to it. (Even if the child element use absolute positioning).
The element is removed from the document normal flow and placed exactly where you tell it to go.