Question

What is definition of Mutation

Answer 1

the changing of the structure of a gene, resulting in a variant form that may be transmitted to subsequent generations, caused by the alteration of single base units in DNA, or the deletion, insertion, or rearrangement of larger sections of genes or chromosomes.
or
the action or process of mutating.

"the mutation of punk's angry energy into something more thuggish and mindless"

Answer 2

sometimes any nucleotide of the gene changes it's position that causes a minor change which is nothing but the mutation. some mutation may be minor some may be considerable.
e.g mutation may cause genetic disorders like sickle cell anemia.

Hope it may be helpful