Both external (worn on the penis) and internal (worn inside the vagina) are available as methods of contraception. 

They act as a barrier during intercourse to stop sperm meeting an egg.

They also reduce the transmission of STIs if used for vaginal, anal and oral sex. 

Condoms are not reusable.

Condoms are 98% effective when used correctly.

They should be applied before any genital contact with another person.

Water based lubricants are safe to use but oil-based lubricants can damage them.

With typical use they are around 80% effective.  

Most people can use condoms.

You may not be suitable if you are allergic to latex (latex free condoms are available), have erectile dysfunction or have distorted vaginal anatomy, or have a physical disability that makes application of a condom difficult.  

Condoms can be used at any time before genital contact.

They are not reusable.

If applied incorrectly, it should be disposed of and a new condom used. 

Condoms are a reliable way to prevent sexually transmitted infections (STI's), and are suitable for unplanned sex.

In most cases, there are no medical side effects.

Condoms may split or tear during use.

Some people can be allergic to the material, latex.