The clear property is used to control the behavior of floating elements elements that are positioned
after a floating element will float around it.
This HDMI page shows an example of this the page contains three divs.
One is blue.
The other is red and one is yellow the blue div has a float left property attached to it.
For this reason the text contained in the red div floats to the right.
The right side of the blue div
we can see the text wrap around the blue div
in order to prevent the yellow div from floating to the right as well.
We've put a clear declaration this forces the div below the blue div unlike the red div which does not
have a clear Dec declaration.