What is infertility? How is infertility treated by assisted reproductive technologies like GIFT and ICSI ?

Explanation

Infertility is when a male & a female are unable to produce children inspite of unprotected sexual co-habitation. Such problems can be assisted by reproductive technologies like :
GIFT : Gamete intra-fallopian transfer
Transfer of an ovum collected from a donor into the fallopian tube of another female who cannot produce ova, but can provide a suitable conditions for fertilization and further development upto parturition.
ICSI : Intra-cytoplasmic sperm injection
It is a procedure to form an embryo in the laboratory in which a sperm is directly injected into the cytoplasm of ovum and embryo transfer is carried out.