It is a CSS property, specifies to position html elements towards left or right side.
Default float value is none.

Float left example

<html>
<head>
<style>
div{
    border:2px dotted black;
    width: 200px;
    float:left;
}
</style>
</head>
<body>
<div>
Float left example.
</div>
<div>
Hello
</div>
</body>
</html>

Float right example

<html>
<head>
<style>
div{
    border:2px dotted black;
    width: 200px;
    float:right;
}
</style>
</head>
<body>
<div>
Float right example.
</div>
<div>
Hello world
</div>
</body>
</html>