@ Operator = Indicates that if there is any kind of error occur, then don't display the message in the user's browser. There are people who test this and didn't see the difference even they put the @ or not they still don't see any error in the browser, well just to add up, the reason why this happen is because of the setting in the php.ini file for error output is turn off.
Different hosting company have different setting so to make sure that you don't want to see any ugly script error for the users or hackers(for them to give a clue to infiltrate you site) you can always use the @ operator.
Hope this help.
