CSS3 Opacity

This property sets the opacity level for an element, here we have some opacity-level, Opacity has a default initial value of 1 (100% opaque) and this recommended css3 property, and this describes the transparency level:-
1 is not transparent at all
0.5 is 50% see-through
0 is completely transparent

CSS3 Opacity Property

It's simple but clear code about css3 opacity, we have div with an id(opacity), in the css the same id having some different properties and values bg-color, width, height and opacity value of 0.5. so the element will fade the 50% of color.

<div id="opacity"></div>
#opacity {
	opacity: 0.5;