Forex (foreign exchange) is the market in which currencies are exchanged and priced relative to one another. A quote such as EUR/USD or USD/JPY is always a ratio: one currency cannot be priced in isolation from the other currency in the pair.
How it works
The first currency is the base currency and the second is the quote currency. If USD/JPY rises, one U.S. dollar buys more yen, meaning the dollar has strengthened relative to the yen over that move.
Exchange rates respond to relative interest rates, inflation, economic growth, trade flows, safe-haven demand, and central-bank expectations. Leveraged retail forex adds another layer because small currency moves can create large account swings.
Why it matters
U.S. investors encounter currency risk even without opening a forex account. International stocks, foreign bonds, overseas revenue, travel, and imported goods all transmit exchange-rate moves into dollar outcomes.
The pair direction matters. Saying 'the dollar rose' is incomplete unless you specify against which currency and over what period.
A simple market example
The Federal Reserve's 2026 policy path and changing expectations for other central banks repeatedly moved major currency pairs during the year. Imagine a U.S. investor owning a Japanese asset that gains 8% in yen terms. If the yen weakens 6% against the dollar over the same period, the investor's return measured back in dollars can be much smaller than 8%. The stock thesis and the currency exposure are separate layers of the same cross-border investment. That is the practical reason forex matters even to investors who never place a leveraged FX trade.
Common mistakes
Talking about a currency strengthening without naming the other currency in the pair.
Assuming small daily currency moves make leveraged forex low risk. Leverage can magnify those small moves dramatically.
Frequently asked questions
What does EUR/USD 1.10 mean?
It means one euro is worth about 1.10 U.S. dollars at that quote.
Is exchanging money for a trip the same as leveraged forex trading?
No. Currency conversion and leveraged speculative trading have very different risk structures.
Why do interest rates affect currencies?
Higher expected returns on a currency's assets can attract capital, although growth, risk, and positioning can offset that effect.
Educational content only. Definitions describe common market usage and may vary by jurisdiction, instrument, or institution.