A dollar is a one ounce silver coin. The word dollar comes from the word German word “thal” which means valley. In the 1500s, the most popular silver coins were made in the valleys of what was then the Holy Roman Empire, now the Czech Republic.
At its inception, the United States originally produced one ounce silver coins called a dollar. Then in 1900, the dollar was defined as 23 grains of gold.
In the United States, the central bank issues bank notes that promise to pay an amount of dollars. However, the bank no longer will redeem the bank notes for coin dollars, so the inherent value of a Federal Reserve “dollar” is zero, and the Federal Reserve stole the coins.
See the Wikipedia page for Thaler.