Refinancing a mortgage can help homeowners lower monthly payments, shorten loan duration, or access home equity. It involves replacing an existing mortgage with a new one that has better terms. Homeowners should evaluate their financial situation, consider refinancing costs (typically 2% to 5% of the loan), and calculate the break-even point. Preparing necessary documentation and maintaining communication with lenders during the underwriting process is crucial. Once closed, homeowners can benefit from reduced payments or cash-out options.