What does 110v vs. 220v vs. 230v refer to? What does Phase refer to?

120 volts or vac refers to a level of voltage, don't have 110 in the USA any more. I am using the term level of energy because you are apparently new to the subject, it is also know as electrical potential difference. I am going to leave the explanation of psae to TKrussel, he can likely better explain it than someone like me who read the term in a book and probably only understood half of it. Single phase is used in your home for lighting, appliances and other low power requirement applications.