What is pollution?

Pollution may so many different things from so many sources,
contaminating the air, water, soil, that a simple definition elusive
Pollution is the human-caused addition of many material or energy(heat)
in amounts that caused undesired alteration to water,air or soil.
Pollution is rarely the result of mistreatments of the environment.
The causes of pollution are almost always the byproducts worthy and essential
activities.And the activities include producing crops, providing energy and
transportation, manufacturing products,and of our basic biological functions(excreting wastes)