Information doesn't flow through the internet as freely as it seems. Depending on which country you live in, you may see different content on a web page—or no content at all. As the internet has become the most important public space for everything from protest movements to pornography, governments around the world have started locking it down. And that has given rise to a new field of research: the science of censorship. ScienceInsider caught up with Phillipa Gill, a computer scientist at the University of Massachusetts in Amherst, to find out what's cooking in this online cat and mouse game. She spoke to us yesterday from the Internet Measurement Conference in Santa Monica, California, which she co-chaired. This interview has been edited for brevity and clarity.