Linux random vs. urandom

random vs. urandom
http://stupefydeveloper.blogspot.com/2007/12/random-vs-urandom.html

random and urandom are devices in /dev that provide random data for applications. The main difference between random and urandom is how they are pulling random data from kernel. random always takes data from entropy pool. If the pool is empty, random will block the operation until the pool would be filled enough. urandom will genarate data using SHA(or any other algorithm, MD5 sometimes) algorithm in the case kernel entropy pool is empty. urandom will never block the operation