An interest rate swap is an agreement to exchange interest rate cash flows, typically involving one party paying a fixed rate in exchange for a floating rate from the other party. A currency swap involves exchanging principal amounts in different currencies and paying interest on those principal amounts. Swaps allow parties to transform fixed rate assets and liabilities into floating rate, or vice versa, based on their comparative advantage in borrowing costs in fixed vs floating markets. Swaps can be valued as a portfolio of forward contracts or by comparing the values of fixed and floating rate bonds.