Clarification on PHP

Dear Sir, In PHP books, most use codes such as if ($engine == 2) for example to retrieve data from client ..... in my case, using just if($engine == 2) on my localhost, it cannot retrieve data ....so i use if ($_POST[engine] == 2) it works... i am puzzled....can u please kindly clarify?? Do I have to state $_POST(...) everytime if i need to retrieve data from client? Regards Ellen -- _______________________________________________ Sign-up for your own FREE Personalized E-mail at Mail.com http://www.mail.com/?sr=signup Meet Singles http://corp.mail.com/lavalife