Kraken is a foreign currency exchange that let’s individual traders and institutions in the US and abroad trade fiat currencies like the US Dollar and the Euro against digital currencies like Bitcoin, Litecoin, Ripple, and Ven.
Trading a “pair” means that you can trade Bitcoins (Symbol: XBT) for Dollars (Symbol: USD) and so on.
On Kraken you can currently trade 13 pairs:
XBT/USD (Bitcoins against Dollars)
XBT/EUR (Bitcoins against Euros)
XBT/XRP (Bitcoins against Ripples)
XBT/LTC (Bitcoins against Litecoins)
XBT/XVN (Bitcoins against Vens)
USD/XRP (Dollars against Ripples)
EUR/XRP (Euros against Ripples)
USD/XVN (Dollars against Vens)
EUR/XVN (Euros against Vens)
LTC/USD (Litecoins against Dollars)
LTC/EUR (Litecoins against Euros)
LTC/XRP (Litecoins against Ripples)
LTC/XVN (Litecoins against Vens)
In this video Jesse Powell, founder and CEO of Kraken, gives some details about the service: