If you are familiar with the laws of thermodynamics, you may recognize the second law as dealing with entropy. In the realm of physics, entropy represents the degree of disorder in a system.
In cryptography, entropy refers to the randomness collected by a system for use in algorithms that require random data.
In mathematics, computer science, and physics, a deterministic system is a system in which no randomness is involved in the development of future states of the system.
A Linux machine that has sufficient entropy in its pool will usually contain 4096 bits of randomness.