Banks and other lenders are required to disclose a rate called the APR. What is this rate? Why did Congress require that it be disclosed?

Is APR the same as the effective annual rate (EAR)? Under what circumstance(s) should the two rates be the same? If you were comparing the costs of loans from different lenders who charge interests in different time intervals (e.g., daily, monthly, semiannually, etc.), should you compare their APRs or EARs? Explain your answer.