Opacity css property makes HTML element or Images transparent. It accepts value in between 0.0 to 1.0
Transparent HTML element Example
<html>
<head>
<style>
div {
background-color:red;
height:200px;
width:200px;
opacity:0.2;
}
</style>
</head>
<body>
<div>
Opacity example
</div>
</body>
</html>Transparent image example
<html>
<head>
<style>
img{
opacity:0.5;
}
</style>
</head>
<body>
<div>
<img src="your_image_path" height="200" width="200" />
</div>
</body>
</html>