Question

what is a pollution ????

Answer 1

Hi here is your answer
the action of making the air, water, etc. dirty and dangerous.

Another Defination
Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of chemical substances or energy, such as noise, heat or light. Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants. 
Please mark as brainlist and follow me

Answer 2

it is the contamination in the environment. the pure thing will become impure thing. Pollution started from prehistoric times,

there is no pollution by naturally... we are the pollution maker including you and me