Can Someone Please Explain Collars and Collaring?

So I have always, ever since I first heard about it at 16, been fascinated and interested in collaring and wearing a collar and all that. Do you just wear them for the aesthetic purposes (I have 3 leather choker goth style ones and I think they are so beautiful) or does your person actually attach a chain to them like a lead for a doggie? What is the role of a collar during BDSM acts? Is it a reminder of being owned and cared for? Do you hold the chain while having sex? And as far as collaring, I have heard it's like being or getting married. Is this true?

I really want to learn more about this lifestyle and really get into it. Please tell me about your experiences or anything I should know.

Thank you!