Wife swapping means that the man will trade his wife for another mans wife for awhile or indefinately. Swingers do this practice. Normal people do not do this kind of thing.
Couples "swap" partners and have sex with someone else's husband or wife. People do it in order to have sex with someone else and add excitement or sexual adventure to their lives without technically cheating.
It is exchanging one's wife with someone else's wife just for sometime and the main reason is to get exposure about how other couples interact or solve relationship problems.
"Wife swapping" is an exchange of sexual partners by married couples, typically done to combat bedroom boredom and increase sensual variety. It is a subset of the broader term "swinging."