Fertilization is the process of fusion of male and female gametes to form a zygote. It is a process of sexual reproduction that occurs in plants and animals. In plants, fertilization occurs after pollination and germination. In animals, fertilization occurs when two gametes, sperm and ovum, fuse together to form a zygote. The main purpose of fertilization is to combine the haploid chromosome sets of two individuals into a single diploid cell known as the zygote, which is the result of activation of the egg. The different stages of fertilization in humans include acrosomal reaction, fusion of sperm and egg, and implantation. In plants, the fertilization process can be grouped into three types: porogamy, chalazogamy, and mesogamy. Following fertilization, the zygotes cells start to divide, and it eventually turns into an embryo or growing plant.