The Tor project is a non-profit organization that conducts research and development into online privacy and anonymity. It is designed to stop people – including government agencies and corporations – learning your location or tracking your browsing habits.
Based on that research, it offers a technology that bounces internet users’ and websites’ traffic through “relays” run by thousands of volunteers around the world, making it extremely hard for anyone to identify the source of the information or the location of the user.
Its software package – the Tor browser bundle – can be downloaded and used to take advantage of that technology, with a separate version available for Android smartphones.
There are some trade-offs to make: for example, browsing using Tor is slower due to those relays, and it blocks some browser plugins like Flash and QuickTime. YouTube videos don’t play by default either, although you can use the “opt-in trial” of YouTube’s HTML5 site to bring them back.