The main function of the sperm in reproduction is to deliver genetic material to the egg, leading to fertilization. Sperm cells are specialized for mobility, enabling them to navigate toward the egg in the female reproductive tract. Through the process of fertilization, which typically occurs in the fallopian tubes, the genetic materials from the sperm and egg combine to form a zygote. This union initiates the development of an organism, making sperm essential for sexual reproduction and genetic diversity in populations.