Refinancing a mortgage involves replacing an existing home loan with a new one, often to take advantage of lower interest rates, alter loan terms, access equity, or consolidate debt. Key steps include choosing the type of refinance, finding a lender, gathering documents, fixing the interest rate, undergoing underwriting, and closing the deal. Ideal times to refinance include when interest rates drop significantly, your credit score improves, or you want to change loan terms. However, refinancing may not be beneficial during high rates or if closing costs outweigh savings.