What a collar means in the BDSM lifestyle is trust. A true dominate (Dom) does not need to be cruel or strict with his submissive (Sub). A collar means that the sub willingly gives of her own free will, not only her body for her Dom’s use, but her soul and her life. It is the Dom’s responsibility to take care of his sub and make sure that she/he can do everything to the best of her ability. There is more intimacy in the sub giving their Dom their collar than most people experience in a happy and long lasting marriage.
I fail to use words to describe how intimate this gift is and yet it is one of the few redeeming qualities of humans. The ability to trust someone to that extent is almost magikal.
Elaboration on this might come later.
Scatterbrained and braindead 
I understand, I think; I’ve dealt with a lack of any trust in relationships, and being able to completely trust someone with everything must feel amazing. I also really like how you explain this. It makes sense to me, yet I have never dealt with anything like this in my sex life.
It is amazing. I have not had the trust to the extent that i have described, but i have come close enough. Unyielding trust is wonderful and is something everyone should have not just for their sex life but for sanaty’s sake.