In the context of Forex trading, a "spike" refers to a sudden and sharp movement in the price of a currency pair, which can occur during major economic news releases or geopolitical events. These rapid fluctuations can result in significant gains or losses in a short period, and traders often need to react quickly to capitalize on or mitigate the effects of such spikes. Due to their unpredictable nature, spikes can also pose risks, particularly for those using high leverage or stop-loss orders.