APR, or Annual Percentage Rate, is a measure used to express the cost of borrowing money or the return on investment over a year. It includes not just the interest rate but also any additional fees or costs associated with the loan or investment, making it a more comprehensive figure for comparison. When considering loans, such as mortgages or credit cards, a lower APR typically indicates a cheaper borrowing cost. Understanding APR helps consumers make informed financial decisions by allowing them to compare different loan offers and choose the one that best fits their needs.