“epi” means “over”; epigenetics means “over the range or beyond the range of genetics”.
This term is used for those phenotypic or physiological changes in genetics which may not be heritable. The term genetics is used, because changes may alter the genetic function.
In epigenetics, cytogenetics and phenotypic changes generally occur due to histone modification, and changes in DNA methylation. It has nothing to do with the sequence of DNA. So, different alleles which experience epigenetics effect have same genotype and produce the same amino acid sequence.
When the particular cell in which epigenetics phenomenon has occurred, divides further, the epigenetic effect is also transferred to the newly divided cell. But this effect lasts only till that time
Epigenetic effect is never spontaneous. It is not a mutation. It is a type mutation; more properly known a paramutation.
Sometimes epigenetic effect may be lethal (cause death of the organism having it).