The IMF is the International Monetary Fund, a big club of countries that looks after the world's money system. It was set up after the Second World War. Learner books often say it 'encourages trade' and 'helps poorer countries grow'. That is a bit mixed up, though actually. Trade rules belong more to the WTO. Long, slow help for a poor country to build roads and schools belongs more to the World Bank. What the IMF really does, most of the time, is step in when a country's money is in trouble — when it cannot pay what it owes, or its money is falling apart. It lends, but the loan often comes with hard 'please change how you run things' conditions (spend less, tax more, fix the banks). So some people call it a firefighter; others call it a bossy lender. In news you write the letters after you have said the name once. It is a proper name, not a normal noun.