The main function of reproduction is to make sure that people will be able to make certain species survive. There are a lot of living things who would like to make sure that their lives will go on and on. The reproductive system of males and females would have different functions.
The female reproductive system will be in charge of releasing the egg while the male reproductive system will be releasing the sperm. When a sperm successfully penetrates the egg, that is the time when fertilization will occur. Just remember that it does not mean that just because fertilization has already occurred, this will continue. There are some instances when fertilization will happen but will not continue.