What is Over- and Under-Blocking

Technical censorship techniques are subject to both over- and under-blocking since it is often impossible to always block exactly the targeted content without blocking other permissible material or allowing some access to targeted material and so providing more or less protection than desired.

Internet Censorship in China

Treasa Nic Giolla Chomhaill (Computer Science Department, Letterkenny Institute of Technology, Ireland), Nigel McKelvey (Computer Science Department, Letterkenny Institute of Technology, Ireland), Kevin Curran (School of Computing and Intelligent Systems, University of Ulster, Northern Ireland), and Nadarajah Subaginy (School of Computing and Intelligent Systems, University of Ulster, Northern Ireland)