As opposed to fiat money, a gold standard is where every currency note is backed by a certain amount of gold, hence the name.
The US was on a gold standard for its currency up until (US President) Nixon closed the gold exchange window in 1971, thereby freeing the price of gold with respect to the US dollar and allowing gold to rise in price. The price of gold went from US$35/ounce to US$800/ounce by 1980.