The Teeter-Totter
Gold is priced in US Dollars. Therefore, mathematically, when the dollar gets stronger, it takes fewer of them to buy an ounce of gold (price goes down). When the dollar gets weaker, it takes more (price goes up).
What is the DXY?
The DXY measures the strength of the USD against a basket of foreign currencies (Euro, Yen, Pound, etc.).
Important: The dollar can look "strong" on the DXY just because other currencies are collapsing faster. It's like being the cleanest shirt in the laundry basket.
Gold in Other Currencies
Always check the price of gold in other currencies. Often, gold will be hitting all-time highs in Yen or Euros while looking flat in USD. This signals that the demand for gold is real, but the strong dollar is masking it temporarily.