Condoms, or sheaths, are made of latex (rubber) and often have spermicide on the outside. They are put on a man's erect penis before intercourse to stop the sperm entering the woman's vagina.

The history
Condoms in one form or another have been used for centuries and they are one of the oldest forms of ‘barrier' contraception. According to legend, King Minos of Crete used a goat's bladder. The Romans also used bladders to protect against sexually transmitted diseases (STDs), the Chinese used oiled silk, and the Japanese used leather or a cap of tortoiseshell. Other cultures have used materials such as linen, and animal intestines.

In the mid 19th century, a crêpe rubber solution was used. However, in the 1930s, the manufacturing process changed when the crêpe rubber solution was replaced with liquid latex. Most of today's condoms are still made of very fine latex — some with inbuilt spermicide or lubricant. As well, manufacturers are continuing to investigate alternative materials such as polyurethane.

Condoms now come in different sizes, thicknesses, flavours, textures and colours, however, it should be noted that novelty condoms are not always a reliable form of contraceptive or protection against STDs.

How do they work?
A condom is put on a man's erect penis before intercourse to stop the sperm, semen, vaginal fluids and sexually transmitted diseases (STDs) being transmitted between sexual partners. Along with other barrier methods of contraception, condoms can help prevent sexually transmitted diseases and may be used for this purpose alone.

If possible, they should always be used with lubricants to make them less likely to break. Use only water-based lubricants — others can damage the condoms. Non-lubricated condoms are available for those people who are sensitive to the lubricant.

What are the advantages and disadvantages?
Condoms are relatively cheap and easy to buy, but they can break or slip off. The man also has to withdraw soon after climaxing (ejaculating) and must hold the condom on his penis while withdrawing, to prevent any leakage of sperm.

Apart from contraception, their main advantage is that they can provide some protection against getting a sexually transmitted disease, including HIV and AIDS. They are also easy to use and there are no side effects.

How effective are they?
If used correctly, condoms can be 98-100 per cent effective in preventing pregnancy from occurring. If not used correctly, the rate can be much lower.