Form tag is used at those pages where we are taking inputs from users.
We will tahe example here of asp.net (a server side language) where
form tag is used for controls to be used in page. Without form tag we
cant use any control on page.
Syntax is
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Frame set example</title>
</head>
<body>
<form>
My controls will come here
</form>
</body>
</html>
Controls can include checkbox, labels, textboxes, dropdowns, radio buttons etc.