Some websites are “Reader” enabled – which gives you a distraction-free, mobile-friendly reading experience on your iPhone/iPad. In the past (iOS 6), Reader Mode was enabled by tapping on the big blue “Reader” button on the right-side of the address bar.
Things have changed – slightly – in iOS 7. Some folks have been asking about the missing “Reader” button in Safari (on all iOS 7 devices). Here's where that button is now:
As shown in the below image, both on the iPhone/iPod Touch and the iPad, the Reader button is now a simple icon that resembles a paragraph representation. Tapping on the icon enables the reader mode which you're looking for.
This is just a minor, cosmetic change but since a large text-filled button is replaced by an unfamiliar icon, things are not as intuitive as before. While this does mark a bad move, I think this was done to make the design flow smoother.
The reader-mode is not available on all websites. Only a few websites have that feature enabled by default which allows Safari to make the whole website render differently – in a more readable, distraction-free manner.
Alternatively, in iOS 7, Safari switches to a distraction-free full-screen mode when you switch to the landscape mode. While in iOS 6, you had those maximize and back buttons displayed on the bottom part of the screen, iOS 7 sacrifices them for readability. You can go back or quit the full-screen mode by swiping left-to-right or by changing the orientation respectively.
There are other tricks and changes in Safari that you might want to read about, to make your Safari experience in iOS 7 better and more productive. Check out these: