Mortgage refinancing replaces an existing mortgage with a new one to lower interest rates, reduce monthly payments, or shorten loan terms. Key considerations include current rates, home equity, credit score, and refinancing costs. Refinancing can switch adjustable-rate to fixed-rate loans or enable cash-out for expenses. Typically, a credit score of 620+ is needed. Evaluate savings against fees and how long you plan to stay in the home before refinancing.