What is the password on sonic for?

It depends, I only know the answer if its for Ultimate Sonic Flash. In Ultimate Sonic Flash, you click on the Get PassWord Button and make sure you've written down the passWord on a piece of paper. Then type in the passWord in the box. So far, I've only used it to be Shadow the Hedgehog. I also know that it allows you to be two people. Though I haven't used that before.