Slide 14 There are three types of condom materials  natural materials, latex rubber and plastic. The earliest condoms were sheaths made from animal intestines, bladders and skins. These natural condoms have been used for thousands of years and are still available in some countries. While they are an effective barrier against sperm and bacterial STDs, they are not as effective against viral organisms such as HIV, which are smaller than bacteria. Natural condoms allow the transfer of body heat between partners. Rubber condoms were developed in the 19th century, followed by latex rubber in the 20th century. They are less porous than natural condoms and, hence, form a more effective barrier that can block smaller organisms, such as HIV. However, latex condoms reduce heat transfer, which may contribute to reduced sexual pleasure. Various types of plastic male condoms are under development, and one brand is on the market in the United States and Europe. Plastic condoms provide an effective barrier against HIV as well as bacterial STDs, while at the same time allowing better transfer of heat. Since most condom users are still using latex condoms, the information described in this presentation refers to the latex rubber condom unless otherwise specified.