Can be a complex method. No protection from STDs. Latex is best, polyurethane for people with latex allergy. Condom holds sperm, preventing its deposition into the vagina. Female condoms are also available.
Motivation is essential.
May decrease sensation for some. A new condom should be used each time. Used in combination with a spermicide. Can be inserted before intercourse and left in place 8 hours after intercourse. Some protection against STDs, tubal infertility, and cervical cancer.