Currency pairs in forex are the quotation of two different currencies, showing how much of the quote currency is needed to purchase one unit of the base currency. They are the fundamental trading instruments in the foreign exchange market, where one currency is exchanged for another. Currency pairs are categorized into major pairs (like EUR/USD, USD/JPY), minor pairs (like EUR/GBP, AUD/NZD), and exotic pairs (like USD/TRY, USD/SGD) based on their trading volume and liquidity. Traders analyze currency pairs using technical and fundamental analysis to speculate on price movements and profit from fluctuations in exchange rates.