The CSS position property can be used to define where an element is rendered on the current screen, and whether that element should move when page content is scrolled.
static - This is default. Elements renders in order, as they appear in the document flow. Regardless of what left/top CSS properties you define, the element will always be layed out.
absolute - The element is positioned relative to its first positioned (not static) ancestor element.
fixed - The element is positioned relative to the browser window.
relative - The element is positioned relative to its normal position, so "left:20" adds 20 pixels to the element's LEFT position.