Market categories
Foreign exchange prices one currency against another and is commonly quoted as a bid and an ask.
In a pair such as EURUSD, the first currency is the base currency and the second is the quote currency. A rising price means one unit of the base currency buys more of the quote currency; a falling price means it buys less. The difference between the displayed bid and ask is the spread.
Interest-rate expectations, inflation, employment data, central-bank communication, political events, and changes in risk appetite can all affect exchange rates. Liquidity and spreads can also change around market openings, scheduled announcements, holidays, and periods of unusual volatility.