Passcode useful to prevent Hackers?

As I understand it, if your iPhone is not jail broken the chances of getting a virus or being hacked is virtually nil.

 

I don't think that the passcode will prevent hackers.

The passcode will prevent somebody else that has physical access to your phone to look at any of your stuff. Or to send a message, mail in your name...

So put on the passcode and set also the automatic lock. To prevent others from misusing you device when you forgot it somewhere or are asleep.... It will also prevent children or other family members from spying in your personal stuff. of course as long as you don't tell them the code.