What is the correct way to disconnect a car battery? and then the correct way to connect it back?

My dad and i have had many disputes about how you should take the negative battery terminal off first when taking the battery out or installing stereo system stuff, or to take the positive off first. If you take the negative off first then he said that would not make sense because it will spart if it happens to... show more My dad and i have had many disputes about how you should take the negative battery terminal off first when taking the battery out or installing stereo system stuff, or to take the positive off first. If you take the negative off first then he said that would not make sense because it will spart if it happens to accidently touch another piece of grounded metal. Then once the battery is off, what is the correct order to put it back on?