Contraception is the use of hormones, devices or surgery to prevent a woman from conceiving.
Contraceptives may be barrier, spermicidal, or hormonal. Barrier methods are condoms, sponges or diaphrams which prevent the sperm and egg from meeting and thus prevents fertilization. Spermicidal methods use a chemical which will kill sperm on contact. The standard birth control pill affects the female's hormone levels to prevent release of the egg cells and reduces or eliminates the monthly period.
A more permanent method is a vasectomy for men and tubal ligation for women. This cuts the tubes that deliver sperm or the egg cells.
Other birth control methods either prevent the embryo from implanting in the womb or remove it after implantation. These methods do not prevent conception, and cannot be considered contraception