The wedding, the marriage license, the ceremony.
What does it all mean to you and to the other person?
For some people it is just a piece of paper. For others a license, or permission to have sex. For others it is a statement that you will be with this person as long as both of you are still alive. Whatever you are thinking this is the way the outside world looks at it.
You have just made a contract that has legal ramifications. It isn’t just between the two of you. You have involved the whole legal system in your life. To the people who come to your wedding, you are stating that this is the one person who plan to be with. If it blows apart, they will question whether you can keep your word. If you blow apart a second or third marriage, they will know for sure that your word is no good.
What you do in Vegas might stay in Vegas — good luck with that, but when you say I do in a wedding everyone knows what you said, and they will judge you by how you live that out.
A piece of paper. No a statement from you in front of everyone you love and like, and that you are related to.