What is the international reserve currency that has been in use since 1944?

The U.S. Dollar has been the international reserve currency since the Bretton Woods Conference in 1944. This conference established a new global monetary order following World War II, where countries agreed to fix their currencies to the U.S. Dollar, which was, at that time, convertible to gold. The U.S. Dollar's role as the primary reserve currency was reinforced by the size and strength of the U.S. economy, extensive international trade conducted in dollars, and the stability of U.S. financial markets. As a result, many countries hold significant reserves of U.S. Dollars to facilitate international trade and to ensure economic stability.

In contrast, while the Euro and Pound Sterling are widely used, they have not been the predominant international reserve currency since 1944. The Japanese Yen is also a significant currency, but it does not hold the same level of global reserve status as the U.S. Dollar. Hence, the U.S. Dollar maintains its position as the key currency for international trade and finance.