This chapter explains the difference between contraception and contragestion as general methods of birth control. It discusses the methods of birth control for which the man is primarily responsible, including potential side effects, and the methods of birth control for which the woman is primarily responsible, including potential side effects. Birth control is a topic with both personal and societal implications. Apart from refraining from sexual activity, the most direct method of preventing birth is to interfere with the union of the sperm and egg. The chapter presents decreasing order of efficacy the methods of birth control in use and the various methods of induced abortion and when during pregnancy they are usually used. The cervical mucus method is based on a change in the consistency of cervical mucus around the time of ovulation. Diaphragms and cervical caps physically prevent sperm from entering the cervical canal.