A zygote is the initial cell formed when a sperm cell from a male fertilizes an egg cell from a female. This single cell contains genetic material from both parents, combining their DNA to create a unique organism. The zygote is the first stage of development in sexually reproducing organisms, including humans, animals, and plants. After fertilization, the zygote undergoes a series of divisions and transformations, eventually developing into an embryo. This process is crucial for the growth of multicellular organisms, as the zygote will continue to divide and differentiate into various cell types, leading to the formation of tissues and organs in the developing organism.