A condom is a sheath-shaped barrier device, used during sexual intercourse to reduce the probability of pregnancy or a sexually transmitted infection (STIs). There are both male and female condoms. With proper use—and use at every act of intercourse—women whose partners use male condoms experience a 2% per-year pregnancy rate. With typical use the rate of pregnancy is 18% per-year. Their use greatly decreases the risk of gonorrhea, chlamydia, trichomoniasis, hepatitis B, and HIV/AIDS. They also to a lesser extent protect against genital herpes, human papillomavirus (HPV), and syphilis.
The male condom should be rolled onto an erect penis before intercourse and works by blocking semen from entering the body of a sexual partner. Male condoms are typically made from latex and less commonly from polyurethane or lamb intestine. Male condoms have the advantages of ease of use, easy to access, and few side effects. In those with a latex allergy a polyurethane or other synthetic version should be used. Female condoms are typically made from polyurethane and may be used multiple times.
Condoms as a method of preventing STIs have been used since at least 1564. Rubber condoms become available in 1855, followed by latex condoms in the 1920s. They are on the World Health Organization’s List of Essential Medicines, the most effective and safe medicines needed in a health system. The wholesale cost in the developing world is about 0.03 to 0.08 USD each. In the United States condoms usually cost less than 1.00 USD. Globally less than 10% of those using birth control are using the condom. Rates of condom use are higher in the developed world. In United Kingdom the condom is the second most common method of birth control (22%) while in the United States it is the third most common (15%). About six to nine billion are sold a year.
Source : https://en.wikipedia.org/wiki/Condom