Voyeurs are people who get sexual enjoyment from watching others. The people they watch can be involved in a sexual encounter, can be partly dressed, naked or dressed in any way that the voyeur finds appealing. The people voyeurs watch may or may not know that they are being watched. Those who know they are being watched and enjoy it are called exhibitionists.
There are many forms of voyeurism. A recent sexual activity in the UK called dogging involves exhibitionists, who have public sex with strangers in places like the woods, being watched by voyeurs. The exhibitionists often post the location where they intend to have sex on the internet or else go to places known for dogging so they can enjoy the knowledge that they will be watched by voyeurs. There are many websites featuring supposedly hidden cams that show men or women undressing in locker rooms, restrooms and many other locations. Some hidden or toilet cams show men or women urinating or tanning naked in tanning beds. Some men or women might masturbate while they watch other people in intimate or what they believe are private situations. Some men who peek into people's windows are referred to as "peeping toms" and in many locations are in violation of the law.