BDSM
Bondage is the use of items like handcuffs, ropes or chains to keep a willing person from moving. Bondage often has to do with sex, but not always. Bondage is done because some people like the feeling of being not able to move while having sex. In this case, bondage sometimes has to do with BDSM, as often in the case of rope bondage and bondage of the female breasts. The letter "B" in BDSM stands for "bondage". Bondage may also be done just because people may like the feelings it creates.