Slaves are submissives who totally give all control over to their Master/Mistress. The main difference from other submissives is that they hand over control of all their life, 24/7 to their top. There can be pre-agreed exceptions to this rule. For the purposes of work for example but by vast majority a slave hands over all decision making to their Dom.
BDSM slaves are happiest when serving a Dominant. They tend to not have limits with their Master/Mistress. This is because their dynamic is very close. The Dominant knows his/her slaves limits and keeps to them.
This is a very unique relationship and is one to build up to. Slaves start out as submissives first and after time become a slave. Slaves, even more so than submissives, tend to wear some kind of symbol of their BDSM slave status. This can be a collar or a piece of jewellery that symbolises their belonging to their Dominant.
Slaves give complete trust to their Dominant, freeing their minds from worry and responsibility. It is a very unique roll and one that only certain submissives can take on.