Do you know your PHP.INI file

variable_name = "value";  

For example

max_execution_time = 36000;

register_globals: This is an internal PHP setting which will give access to the all array elements form $_REQUEST variables as register variables. For example, if we have HTML form containing two input fields email and password then when we submit the form than normally we access the variable email like

$email = $_POST['email']; //for accessing email
 &&
$password = $_POST['password'];//for accessing password from the post

but if register_globals is on then you can access the this with $email && $password as below

// at the very beginning of the script we can use variables like .
$get_email = $email;
$get_password = $password;
//In other words, this expression 
if($email === $_POST['email']) {
  return true;
 } else {
  return false;
}
// this will return true.

memory_limit: This variable has the value Max amount of server memory allowed to consume that is used to open a single PHP script.

memory_limit = 64M; // value in Mega Bytes

When script exceeds the memory allowed, the error output looks something like this:

Fatal error: Allowed memory size of x bytes exhausted (tried to allocate x+y
 bytes) in /path/to/php/your/running/script

or like this:

PHP Fatal error: Out of memory (allocated x) (tried to allocate x+y bytes)
 in /path/to/php/your/running/script

This are used to control file size limit to users to the maximum upload file size for PHP scripts. Although if we want to make a change as per our need we can make it by these two variables change the upload_max_filesizeand post_max_size directives.

upload_max_filesize = 50M;
post_max_size = 51M;

Important: Always remember that if you want that file uploads to work perfectly, the post_max_size directive should be a little larger than the upload_max_filesize

magic_quotes_gpc: This is A Magic Quotes process which is used to escapes incoming data to the PHP script automatically. But this is not the preferred way to code with magic quotes on, instead do it is better to escape the data at runtime, so this one is having the value off.

magic_quotes_gpc = off;

Warning: This feature is DEPRECATED as of PHP 5.3.0 and REMOVED as of PHP 5.4.0.

mysql.connect_timeout: This is to set maximum execution time limit for sql query of that you script can take.By default which is 30 seconds but we can adjust this y writing as beklow.

mysql.connect_timeout = 60; // values in the seconds