Fertilization is the biological process in which male and female gametes (sperm and egg cells) combine to form a zygote. This process can occur through sexual reproduction, where sperm fertilizes the egg, leading to the development of an embryo. Fertilization is crucial for sexual reproduction in most organisms, including plants and animals, and it marks the beginning of a new organism's life cycle. In addition to natural fertilization, artificial methods, such as in vitro fertilization, are also used in reproductive technologies.