Fertilization refers to the integration process of male and female gametes to generate the diploid zygote.
There are basically two types of fertilization: external and internal fertilization.
External fertilization refers to the fertilization of an egg by the sperm exterior of the body of an organism.
External fertilization prevails in aquatic environments.
Amphibians and fishes implement external fertilization by releasing male and female gametes into the water.
Internal fertilization refers to the fertilization of eggs by the sperms in the female reproductive tract.
Internal fertilization persists within the female body.
Mammals and birds conduct internal fertilization.
Final Answer:
Two types of fertilization are external and internal fertilization.