Oral contraceptive pills contain estrogen and progesterone hormones, so they alter the ovulatory cycle and mainly prevent ovulation. Condoms are physical barrier, they prevent the sperms reaching cervix. Vasectomy is the surgical and terminal method of birth control in males. They do not prevent sperm production, but hinder sperm transport so the semen will not contain any sperms. IUDS e.g. Copper-T prevent fertilization and mainly implantation.
