Using HTML meta tags: we can prevent Web browsers caching.

<meta content="Sun, 20 Fed 2000 01:11:11 GMT"
/>
<meta http-equiv="Pragma" content="no-cache" />

Here  free trial offer Meta tag tells the browser, cached copy of the page in back date.That means   browser should never cache the page.

But some browser does not support this approach .If you are working with php and include the header that has Meta definition.

For this case, use php Header function to produce the two meta tags above

<?php
header('Expires: Sun, 20 Fed 2000 01:11:11 GMT');
header('Pragma: no-cache');
?>

Or use

<?php
header('Expires: Sun, 20 Fed 2000 01:11:11 GMT');
header('Cache-Control: no-store, no-cache, must-revalidate');
header('Cache-Control: post-check=0, pre-check=0', FALSE);
header('Pragma: no-cache');
?>

In this case visitor will always see the latest contents.

using ini_set(‘memory_limit’,’15M’); // now 15M space is  set during run time.

Using string 36 hour ong>ini_set ( string $varname , string $newvalue .
you can change

To   increase the execution time for any php script simple use below code.

ini_set(‘max_execution_time’, 240); //240seconds = 4 minutes

Ans: Following two of the most important  recent changes that affect old code are:
The deprecation of the old $HTTP_*_VARS arrays (which need to be indicated as global when used inside a function or met The following superglobal arrays were introduced in PHP » 4.1.0. They are: $_GET, $_POST, $_COOKIE, $_SERVER, $_FILES, $_ENV, $_REQUEST, and $_SESSION.The older $HTTP_*_VARS arrays, such as $HTTP_POST_VARS, still exist as they have since PHP 3. As of PHP 5.0.0, the long PHP predefined variable arrays may be disabled with the register_long_arrays directive.

Ans: If we used the method GET then our form information would live in the $_GET superglobal instead.
You may also use the $_REQUEST superglobal. if you do not care about the source of your request data. It contains of GET, POST and COOKIE data.

Ans: It makes sure any characters that are special in html are properly
encoded  so people can’t inject into commercial your page.

Ans: Hi <?php echo htmlspecialchars($_POST['name']); ?>.
You are <?php echo (int)$_POST['age']; ?> years old.

A sample output of this script may be:

Hi Joe. You are 22 years old.

Ans:It is a function built into PHP which searches a
string for another string.

Ans:$_SERVER