In the context of the foreign exchange market, traders liquidate their positions in various currencies to take up positions in safe-haven currencies, such as the US dollar. Sometimes, the choice of a safe haven currency is more of a choice based on prevailing sentiments rather than one of economic statistics. An example would be the financial crisis of 2008. The value of equities across the world fell while the US dollar strengthened (see Fig.1). This happened despite the strong focus of the crisis in the US.
Intra-day, a trader must also accept what the market provides at its various intervals. For example, markets are typically more volatile at the start of the trading day, which means specific strategies used during the market open may not work later in the day. It may become quieter as the day progresses and a different strategy can be used. Toward the close, there may be a pickup in action and yet another strategy can be used. If you can accept what is given at each point in the day, even it does not align with you expectations, you are better positioned for success.
Forex is a portmanteau of foreign currency and exchange. Foreign exchange is the process of changing one currency into another currency for a variety of reasons, usually for commerce, trading, or tourism. According to a recent triennial report from the Bank for International Settlements (a global bank for national central banks), the average was more than $5.1 trillion in daily forex trading volume.