A mutation can be defined as the alteration in the single base pair of the DNA. It can be harmful, neutral or beneficial for the organism in which it takes.
Explanation:
Beneficial:
A mutation in the organism that increases its ability to store moisture in a dry condition will prevent the organism from drying out in the extreme conditions.
A color mutation that will increase the chances of sexual selection in the birds is beneficial it can prevent the sexual dimorphism in the offspring produced by the birds.
Harmful:
A mutation in a non coding region is harmful as it can lead to the expression of faulty proteins at inappropriate place.
A mutation in the plant which decreases the plant's ability to grow and gives plant a short height will be harmful because there will be more competition for sunlight.
The mutation that does not changes the protein synthesis but increases white pigmentation on a prey in a snowy environment as it has prevented adaption of the prey and thus this mutation is harmful.