If you are married, are you 'expected' to wear a wedding ring, or is there a law saying you have to, or some other reason?

Having never been married (or engaged to be married) I've never gone down that pathway of planning a wedding or buying symbols of commitment via marriage.

If a person is married, do they have to wear a wedding ring?

Is there any sort of law saying a married person has to wear a wedding ring?

Is there any sort of social convention that expects a married person to wear one?

If a married person chooses to not wear one, is that meant to be representation of something?