\n is the newline character, \t is the tab character. It's usually use for formatting html. eg,
echo "<html>\n<head>\n</head>\n<body>\n\t<div>\n\t</div>\n</body>\n</html>";
will look like:
<html>
<head>
</head>
<body>
<div>
</div>
</body>
</html>
When viewing source 🙂