Master/Dom

Hello thank you for checking out my post.
So i am on a site for fat chub people, and i have been getting messages from people that think i would be a good master/dom and to be honest i have no clue, what that even mean's, one person asked to become a full time live in slave. What the fuck a slave. Yeah im totally lost. i am very upfront with what i want and how i want it but isnt everyone? can anyone explain to me cause if you cant tell this whole master/dom/slave/owner thing, might be a little much for me lol