Your going to hear all sorts of definitions.

I believe its rather simple, submit or do not...how long you submit for, and under what conditions etc, are all things that can be as temporary or as permmament an arrangment as the partners involved have agreed too before hand or are feeling out as they go along...this also includes what they choose to call themselves. Anything from Lord High Dom of Hard Dicking and his slave slipswhenwet to Hi Im Albert and this is my bottom sasha can be just as aplicable .

For some traditionalists who had origins predating the influence of the leatherman there are really only two main catagories on the kneeling side of the bdsm coin: submissives (uncollared bdsm practicioners who submit on occassion) and slaves (those who have given themselves as property, IE "the collared"). Both of which are quite capable of dominating/ topping others without lossing their titular distinctions when required.

The terms top, bottom, and switch were originally derived by and used for despriptions amongst the gay community to describe roles during sex positioning, particularly among men. A top is a person who penetrates, a bottom is one who receives penetration, and a switch (taken by the gays from the baseball term in reference to a "switch hitter") engages in both activities.

Thanks mainly to exposure by the leatherman who helped bring a sort of bdsm revival to america in the 40's and 50's in their own special way and many uninitiated kinskters rising up from the straight communitty of their own voilition adopting their bdsm practices from them directly or making up whatever they wished for themselves (not having any other recourse since they hadnt been selected for inclussion by the highly secretive groups allready in existence) the terminology was adopted in part or in whole later on by some portions of the community and escewed by some others as unnessesary as each say fit for themselves.