As far back as 1350 BC,  there are records of Egyptian men wearing sheaths as decorative covers for their penises.  In the eighteenth century, condom use became popular for protection against infections and unwanted pregnancies. 

The condom is usually made of latex rubber (another name for it is "a rubber") and is meant  to fit an erect penis.  Many condoms come lubricated and/or premedicated with spermicide (a chemical that kills sperm cells on contact). 

Other condoms made of lamb intestines are more expensive and may not protect as well against sexually transmitted diseases.  Condoms are designed to keep semen from getting into the woman's vagina.  To maximize the protective benefits of condoms, they must be used correctly.