Viruses show the characteristics of non- living organisms when they are present outside the living organisms. Such as, survive for billions of years. They can survive very high temperatures, freezing cold etc., cannot move and cannot reproduce. Viruses do not possess any cellular machinery of their own because viruses are acellular and do not havetheir own metabolism, therefore they utilize the machineryand metabolism of the host for the purpose of self- replication.
This is the reason why viruses are not considered to be living. The viruses are not considered to be non living also. They are put somewhere between living ans non- living.
