what is opacity in css3?

[kashifalijugnoo]

Opacity is CSS3 transparent property whose value changes 0 to 1 or 0 to 100(depends on the browser),it can be applied on both text and image.
0 value indicates less transparent or most fade effect.
1 value indicates more transparent or least fade effect.
vice versa for 0 to 100 for IE9 and earlier
Syntex:
property : value
opacity : 0.5;
filter:alpha(opacity=40) // FOR 1E9 AND EARLIER