Tor is available for free download for Windows, Mac, and Linux machines. It runs in the background and by default stays off. When you want to switch it on, you need to change your proxy settings. Proxy settings are modified in your browser settings (Firefox users Tools > Options > Network > Connection Settings) but that can be a bit of a pain. After you have downloaded and installed Tor (which takes about 10 seconds) download the Tor button Firefox plugin which creates a tiny button at the bottom of your Firefox which you can click to turn the Tor proxy settings on and off. (If you don’t use Firefox, you should.)
You’ll want to use Tor whenever you are somewhere you think it might be a good idea to lay low. Many countries in the Middle East and Asia carefully track users online and visiting sites you think are harmless (news, social networking, etc.) could get you in legal trouble or worse. If you are caught in a military coup,keep your online presence quiet using Tor and encrypt your Gmail with this Firefox plugin.
Questions? Ask us in the comments whoever you are!