Tor is a darknet that bounces traffic around the globe via many different machines in different countries in order to hide the users true IP address. This enables one to safely and anonymously browse the web without fear of tracking. You can see the amount of users logged into Tor over the past 2 years peaked at around 800,000 users!
Here are some download links to the software on various platforms:
iOS/iPhone/iPad/iPod Touch: Onion Browser
Load this very webpage in your phone now: