Delegates meeting in New Hampshire in 1944 built a system of pegged but adjustable rates. Members fixed their currencies against the dollar within narrow bands, the dollar was convertible into gold at $35 an ounce for official holders, and the IMF was created to lend to countries in temporary difficulty. Adjustments required consultation rather than unilateral action.
The design gave two decades of stable rates and expanding trade. Its flaw, identified early, was that the world needed more dollars than the US could back with gold, so the system's growth undermined its own foundation.
For traders the relevant point is that speculation on currencies as it exists today barely existed then. There was no meaningful spot-fx market for retail participants, because there were no floating rates to trade.
Example: at $35 an ounce, a country holding $350m of reserves held a claim on 10 million ounces. Once outstanding dollar claims exceeded US gold holdings, that claim was theoretical, which is the tension that ended in nixon-shock.
Related: nixon-shock, free-float, currency-peg, reserve-currency