Description: Selects all elements that are descendants of a given ancestor.
A descendant of an element could be a child, grandchild, great-grandchild, and so on, of that element.
<!DOCTYPE html>
<html>
<head>
<style>
body { font-size:14px; }
form { border:2px green solid; padding:2px; margin:0;
background:#efe; }
div { color:red; }
fieldset { margin:1px; padding:3px; }
</style>
<script src="https://code.jquery.com/jquery-latest.js"></script>
</head>
<body>
<form>
<div>Form is surrounded by the green outline</div>
<label>Child:</label>
<input name="name" />
<fieldset>
<label>Grandchild:</label>
<input name="newsletter" />
</fieldset>
</form>
Sibling to form: <input name="none" />
<script>$("form input").css("border", "2px dotted blue");</script>
</body>
</html>