Forex is the financial market where currencies are exchanged at exchange at variable rates. The investor can simultaneously buy one currency and selling the other.
Most often, the exchange rate of one currency is in relation to other is due to the financial or economic conditions of the both countries and the Recent announcements of the countries relative to another. Specifically, investors are betting on a currency if a country or region has a high growth rate for example, or if the interest rates set by central banks are high. This is logical because these two scenarios are indicators of economic health of the country or region.
If the demand for a particular currency is more then it appreciates more in the market. The interest for a particular currency among the investors are have several reasons, typically the investor wants to preserve their capital (For example, the investor sell dollar and buy the Swiss franc which is a stable currency) and or to make a profit by selling foreign exchange (by selling the currency, which appreciates over time).
In the same vein, when a currency is sold massively, it depreciates. Besides, we can cite a happening in September 1992the genius of George Soros, who sold short for 10 billion pounds. This striking force has forced the Bank of England to devalue the pound by about 15%. Thus, George Soros was able to buy sterling at a lower price (earned1.1 billion profits). It has been known as the man who broke the Bank of England.