What is a util?
It is an imaginary unit of satisfaction used to illustrate the logic of choice. It is a real unit of satisfaction that can be measured in a person's brain waves. It is a real unit of satisfaction but it cannot be measured (yet). It is a measure of how useful something is and can be used to separate true needs from wants.
A budget constraint:
illustrates the utility people get from goods. tells how much debt the federal government will have to issue. is a relationship between price and the amount people will buy. separates combinations of goods that are affordable from those that are not.