Why do I want a "Proxy Service"?
Proxy services are useful because your movements on the web are tracked on every website you visit. It may seem innocuous, but taken in aggregate - well, you get the picture. The data is routinely examined for things like personal interests and tastes, and advertisers are racing to present you with the most personalized ads. And there is a darker side - hackers can use this information to determine where you work, what your position likely is, and provides a map back to your company's network.
Tor, and other proxy services, anonymize your connection so that no web server ever knows where you came from. It also blocks tracking services ("cookies") and leaves no traces on your computers hard drive about your online activities.
Orbot is a free proxy service for your Android devices. All services - web, Facebook, Twitter, and more are encrypted and routed through the Tor network for a completely anonymous experience.