Basis points (BPS) are a key measurement in mortgage interest rates, representing 1/100th of a percentage point (0.01%). They help clarify small rate changes, which can significantly impact mortgage payments. For instance, a 25 basis point increase on a $300,000 mortgage can raise monthly payments by $42.94. Basis points are crucial for understanding shifts in interest rates, affecting various financial instruments like stocks and bonds. They provide insight for making informed financial decisions regarding mortgages and investments.