Fertilizations  is the fusion of male and female gamete to form zygote. There are two types of fertilization :
i. Internal fertilization - is the fertilization in which the male releases his sperms into the body of the female and fertilization takes place inside the female body. For example fertilization in human beings.
ii. External fertilization - is when the male and female release their gametes out in open and fertilization occurs outside the female body. For example -fertilization in frog and fish.