The foreign exchange market is where currencies are traded. Currencies are important to most people around the world, whether they realize it or not, because currencies need to be exchanged in order to conduct foreign trade and business. If you are living in the U.S. and want to buy cheese from France, either you or the company that you buy the cheese from has to pay the French for the cheese in euros (EUR). This means that the U.S. importer would have to exchange the equivalent value of U.S. dollars (USD) into euros. The same goes for traveling. A French tourist in Egypt can't pay in euros to see the pyramids because it's not the locally accepted currency. As such, the tourist has to exchange the euros for the local currency, in this case the Egyptian pound, at the current exchange rate.
Factors like interest rates, trade flows, tourism, economic strength, and geopolitical risk affect supply and demand for currencies, which creates daily volatility in the forex markets. An opportunity exists to profit from changes that may increase or reduce one currency's value compared to another. A forecast that one currency will weaken is essentially the same as assuming that the other currency in the pair will strengthen because currencies are traded as pairs.
Fear – Traders become fearful of entering the market usually when they are new to trading and have not yet mastered an effective trading strategy like price action trading (in which case they should not be trading real money yet anyways). Fear can also arise in a trader after they hit a series of losing trades or after suffering a loss larger than what they are emotionally capable of absorbing. To conquer fear of the market, you primarily have to make sure you are never risking more money than you are totally OK with losing on a trade. If you are totally OK with losing the amount of money you have at risk, there is nothing to fear. Fear can be a very limiting emotion to a trader because it can make them miss out on good trading opportunities.
Since the market is made by each of the participating banks providing offers and bids for a particular currency, the market pricing mechanism is based on supply and demand. Because there are such large trade flows within the system, it is difficult for rogue traders to influence the price of a currency. This system helps create transparency in the market for investors with access to interbank dealing.