This function will used for turn on output buffering.if buffering is ON no output is sent from the script (other than headers) instead the output is stored in an internal buffer.
The contents of this internal buffer copied into a string variable using in ob_get_contents(). To output what is stored in the internal buffer, use ob_end_flush(). ob_end_clean() used for used discard the buffer contents.
example of ob_start():
<?php
ob_start();
?>
<html>
<head>
<title>Ob start </title>
</head>
test
</body>
</html>
<?php
echo ob_get_contents();
?>
it will get output : test test
