Fertilization is defined as the fusion of male gamete (sperm) with a female gamete (an ovum or egg) to form a zygote during sexual reproduction. 
Two types of fertilization: External and Internal.

External fertilization:-


 1)The fusion of male gamete and female gamete occurs outside the body


 2)Both individuals discharge their gametes outside the body. 

3)Development occur outside the body. 

•External fertilization occurs in Fish, Toads, and Frogs (amphibians)


Internal fertilization :-


1)The fusion of gametes occurs inside the body.

 2)Only male discharges sperms into female genital tract.

 3)Development occurs inside the body.

• Internal fertilization occurs in Human, cattle, Birds etc. The site of fertilization in human beings is in the fallopian tube of female reproductive system.

Fertilization are of two types : Internal and external fertilization. EXTERNAL FERTILISATION:(1)It involves the fusion of the male and female gamete outside the female body.(2)Chances of survival of the offspringare less.Therefore,a large number of eggs are produced.(3)Dish,Frog,Starfish are organisms showing external fertilization. INTERNAL FERTILISATION:(1)It involves the fusion of the male and female gamete inside the female body.(2)Chances of survival of the offspring are more.Therefore, a small number of eggs are produced.(3) Human,Cow,Hen are organisms showing internal fertilization.