All real estate transactions must be in writing. A quitclaim deed is one way to transfer real property such as a house, land, or certain mobile homes.
Not reversible. Once you give up your claim, you can’t just reverse it.
A quit claim deed delivers the grantor’s (your husband’s) interest in your home to the grantee’s (both of you I assume). It’s merely the easiest way to add you to the home’s title. It does not add you to the loan, but would certainly make life easier if your husband were to pass away as you could avoid having to go through the probate process to get clear title to the home.
Interesting fact is that someone can give a quit claim deed to another on a property they do not even own. Quit claim deed is worthless, of course. Anyone buying a home should insist on a warranty deed rather than a quit claim deed for this very reason.