New Delhi, Aug. 3 -- When the US Federal Reserve left its benchmark interest rate unchanged in the 3.50% to 3.75% range on 29 July, investors across the world watched the decision closely.

The attention reflects the US dollar's central role in the global financial system. As the world's most widely used currency for trade, commerce and central bank reserves, movements in US interest rates ripple across global markets. Those effects eventually reach India, influencing the rupee, stock and bond markets, borrowing costs and, ultimately, your investments and financial decisions.

One way to understand this is to think of the US Federal Reserve as the world's primary financial valve. When the Fed raises interest rates-or keeps them high-it ma...