Gamete Intrafallopian Transfer (GIFT) is an assisted reproductive technique were the eggs are retrieved from the ovaries just like an IVF procedure. Then the Gametes (Eggs and Sperms) are placed into Fallopian tube with a help of a catheter using a surgical procedure called laparoscopy(as shown in the figure below) where the egg gets fertilized.
Zygote Intrafallopian Transfer (ZIFT) is an assisted reproductive technique were the eggs are retrieved from the ovaries just like an IVF procedure. These retrieved eggs are then mixed with sperms in the laboratory. Then the fertilized eggs (zygotes) are placed into fallopian tube with a help of a catheter using a surgical procedure called laparoscopy(as shown in the figure below). The zygote should eventually be implanted in the uterus and develop into a fetus. 
In vitro fertilization is an assisted reproductive technique were the male sperms and the female eggs are fertilized in a laboratory. The fertilized egg is developed into embryo stage which is then placed into the woman’s uterus with a help of a catheter.
Intracytoplasmic sperm injection (ICSI) is an ART involving the injection of a single sperm into the cytoplasm of an oocyte to achieve fertilization. It is mainly performed for the treatment of couples with male factor infertility and those with poor fertilization with conventional IVF.
ICSI is the only treatment option for couples with severe male factor infertility. It can be performed with ejaculated or surgically retrieved sperm.
Assisted Reproductive Technology (ART), according to WHO, refers to infertility treatments where both eggs (oocytes) and sperm are handled ex-vivo to achieve pregnancy. In conventional ART procedures, the oocytes and sperms are combined in a laboratory ex vivo (i.e. outside the human body) and the resulting embryo (mature and fertilized oocyte) is implanted back into a woman.
Infertility is a disease of the reproductive system caused due to the failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse . In simpler words, it is the state of not being able to produce offspring. In female, it is the inability to conceive, and in male it is the inability to impregnate.
The four major causes for infertility can be classified into:
combined male and female factor
Approximately 40% of infertility cases are due to female factor, 40% due to male factor, and 20% due to a combination of both.
According to the 2017 statistical analysis, in India there are about 30 million couples with infertility as shown in the following Figure.