Federal Sentencing Guidelines are a uniform set of nonbinding rules that all U.S. Attorneys are to use to guide them in making sentencing recommendations in criminal cases. It's ultimately up to the federal judge, however, to use their own discretion to decide how much they want to adhere to them when sentencing a convicted defendant.
Imagine that you are going to buy a car, not from a dealership, but from a private seller. Since there will be no financing involved, you withdraw $30,000 in cash and take it with you to meet the seller.