http://en.wikipedia.org/wiki/Obfuscated_code
Also the links at the bottom of page contain more information
A .NET obfuscator
http://www.preemptive.com/dotfuscator-faq.html#What%20is%20Obfuscation?
Also outlines some benefits of using obfuscation
– reduction application size 20-40% smaller
– Compacted programs often load faster and run in less memory
– moreover, networked distribution of components is more efficient because application size is reduced.