Entropy is defined as a measure of ‘disorder’ in any system, or the measure of the tendency of all systems to lose energy. In physics it involves some fairly complex mathematics. However, in this article the term ‘entropy’ will be used more broadly to represent the tendency of all systems to degrade over time. Or put another way, you can’t get more out of a system then what you put into it (with the possible exception of politicians).
We see entropy all around us. A shiny new car accumulates dents, rust, worn parts. Even if you left it parked in a garage and never used it, time and the elements would slowly destroy it. Further, it would never get ‘better’ than when it first came off the assembly line. Living organisms follow the same rule. No matter how viable the genetic inheritance and favorable the environment, eventually the wear and tear of life causes living systems to degrade. Cosmic creations, like stars, are born out of dust, ‘burn’ brightly for a time, and then perish as their energy is used up.