More specifically, the spot market is where currencies are bought and sold according to the current price. That price, determined by supply and demand, is a reflection of many things, including current interest rates, economic performance, sentiment towards ongoing political situations (both locally and internationally), as well as the perception of the future performance of one currency against another. When a deal is finalized, this is known as a "spot deal." It is a bilateral transaction by which one party delivers an agreed-upon currency amount to the counter party and receives a specified amount of another currency at the agreed-upon exchange rate value. After a position is closed, the settlement is in cash. Although the spot market is commonly known as one that deals with transactions in the present (rather than the future), these trades actually take two days for settlement.
Currency trading was very difficult for individual investors prior to the internet. Most currency traders were large multinational corporations, hedge funds or high-net-worth individuals because forex trading required a lot of capital. With help from the internet, a retail market aimed at individual traders has emerged, providing easy access to the foreign exchange markets, either through the banks themselves or brokers making a secondary market. Most online brokers or dealers offer very high leverage to individual traders who can control a large trade with a small account balance.
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.
However, this can steer you away from a carefully planned trading strategy. Even worse, it could cause you to make rash decisions, with the hope of turning that losing trade around, causing you to lose much more money than you would have if you had just left it to play out. Instead of focusing on the long term plan, your mind wants to focus on making the best out of this short term losing position.
Imagine a trader who expects interest rates to rise in the U.S. compared to Australia while the exchange rate between the two currencies (AUD/USD) is 0.71 (it takes $0.71 USD to buy $1.00 AUD). The trader believes higher interest rates in the U.S. will increase demand for USD, and therefore the AUD/USD exchange rate will fall because it will require fewer, stronger USD to buy an AUD.
The problem is that this is where traders are most likely to succumb to overconfidence bias. It's not uncommon for traders to complete a winning streak and then believe that they can't get anything wrong in the future. To believe this is of course unwise, and is only going to end in failure. Make sure you always analyse your trading sessions and look at your wins and losses in detail.