How to restore an iphone to its default settings? (4s)?

I'm thinking of lending my iphone 4s to a friend while he gets his fixed. But if I do lend it to him I want to give it to him with its default settings (ie no apps, contacts or photos on it).Is there a way I can give it to him without anything on it and when I get it back I can restore everything the way it was before?

Settings > General > Reset > Reset All Settings but I'm not sure if this gets rid of Apps.
To get rid of Apps definitely plug it into your computer, laptop and it should open iTunes if you have it installed. Then go to 'iPhone' or whatever it's called on the sidebar and it should say Restore.

Settings>General>Reset>Erase All Content And Settings. I think this is right, and I'm sure you can do it by connecting your phone to your computer/iTunes to.

Tap the Settings app, go to 'General', then 'Reset' (at the bottom of the page), then 'Erase all Content and Settings'

This deletes absolutely everything you've ever done on the phone, so make sure you have a backup.
Your friend will have to set it up as a new phone (just like when you did when you first got it out of the box)