When Notification Center was first introduced, users were only allowed to access it when the device was unlocked by swiping down from the top of the screen.
With iOS 7 it's now possible to view notifications stored in Notification Center from the lock screen, as well as when the device is unlocked. Of course there are still actionable notifications that appear on the lock screen, , having every single app push notifications to the lock screen is a huge battery drain.
Apple realized a way of getting around the battery drain is to give users the ability to send notifications only to Notification Center, and not the lock screen itself
To access the Notification Center on the lock screen swipe down like you normally would. There you'll find three columns: Today, All, Missed.
The Today column ties into the Calendar, Stocks, and Reminders, and gives you a brief overview of the day's agenda. You'll find that it also provides you with ETA information for frequent destinations, or an address you have included with a calendar appointment.
The All column will hold any and all notifications from apps.
Lastly, the Missed column will host any missed call notifications.
You can customize what information is available in Notification Center on your lock screen in Settings > Notification Center. Here you can disable notifications view (the "All" column) along with the Today view. Turning off the notifications view will only remove the column from the lock screen, and not Notification Center when the device is unlocked. This is a good option for people who are more concerned about privacy than accessing notifications on the lock screen.
In this same settings screen, you can also customize what information appears under the Today view. Disable a category from being displayed in the Today view by sliding the switch next to the respective category to the off position.
Tapping on the Edit button in the upper-right corner of the screen will allow you to rearrange some of the Today view categories.
It's nice to have the option to view notifications on the lock screen in iOS 7. And truth be told, the Today view is more akin to a Google Now-like feature than Apple has let us believe thus far. The first time you open it while at work and see an ETA for traveling back home, you won't be able to help but do a double take.