Guide: How to use Do Not Disturb when your iOS 7 running iPhone is unlocked

Prior to iOS 7 the Do Not Disturb feature only silenced notifications when your device was locked or in sleep mode. Fortunately, iOS 7 has changed that and made it possible to suppress notifications even when you're actively using your iPhone.
Here's how:

• Launch the Settings app from the Home screen of your iPhone.
• Scroll down and tap on Do Not Disturb.
• All the way to the bottom under the Silence section, tap on Always.

That's all there is to it. Your iPhone will now silence all notifications, not just the ones that come in when your iPhone is locked.

via iMore