The spot market is where currencies are bought and sold at their current market price. The prices of currencies fluctuate consistently, many times by only a tiny fraction of their current value. A mixture of economic, political, and supply/demand affect the price of currencies, and markets are exceptionally liquid for primary trading pairs around the world.
You can profit from this! A lot of the major pairs like EURUSD, GBPUSD and USDCHF experience massive movements and specific patterns during this time. In fact, I created a holistic trading strategy for the GBPUSD just based on this one fact. The strategy is called Simple System v6.0 and you can find it in this course. It uses an extremely profitable pattern that I discovered for GBPUSD.
The value of a country's currency depends on whether it is a "free float" or "fixed float". Free floating currencies are those whose relative value is determined by free market forces, such as supply / demand relationships. A fixed float is where a country's governing body sets its currency's relative value to other currencies, often by pegging it to some standard. Free floating currencies include the U.S. Dollar, Japanese Yen and British Pound, while examples of fixed floating currencies include the Chinese Yuan and the Indian Rupee.
Investment management firms (who typically manage large accounts on behalf of customers such as pension funds and endowments) use the foreign exchange market to facilitate transactions in foreign securities. For example, an investment manager bearing an international equity portfolio needs to purchase and sell several pairs of foreign currencies to pay for foreign securities purchases.
In the futures market, futures contracts are bought and sold based upon a standard size and settlement date on public commodities markets, such as the Chicago Mercantile Exchange. In the U.S., the National Futures Association regulates the futures market. Futures contracts have specific details, including the number of units being traded, delivery and settlement dates, and minimum price increments that cannot be customized. The exchange acts as a counterpart to the trader, providing clearance and settlement.