Gold is the only asset that appears on the balance sheets of central banks worldwide without simultaneously being the liability of another institution. This property — being nobody's debt — is the core reason it has functioned as a reserve asset for millennia.
Every other financial asset involves a counterparty. A government bond is a claim on a government's future tax revenue. A bank deposit is a claim on the bank. Gold requires no such trust — it exists independently of any institution's promise to pay.
Central banks collectively hold over 35,000 tonnes of gold as of 2024, a figure that has been rising since the 2008 financial crisis. This accumulation reflects a desire to hold reserves that cannot be frozen, sanctioned, or devalued by another government's monetary policy.
Silver shares some of gold's monetary history but has a larger industrial footprint — used in solar panels, electronics, and medical devices — which makes its price behaviour more complex and more closely tied to industrial demand cycles.
Both metals are most usefully understood as monetary phenomena, not just commodities.