The tweets still fly and the videos hit YouTube whenever protesters take to the streets in Iran -- even as the Internet battle there turns more grueling. Authorities appear to be intensifying their campaign to block Web sites and chase down the opposition online, and the activists search for new ways to elude them.
Software tools that bypass censorship and surveillance, also known as circumvention technology, are used in variety of contexts. Chinese citizens get around the Great Firewall to access censored sites and popular international social media platforms. Activists in Iran bypass government surveillance to post photos and video of anti-government demonstrations.