The monetary unit is the Krona ( pl. kronor); one Krona=100 Öre.
Bank notes are printed in values of 20, 50, 100, 500 and 1,000 kronor. Coins are 1, 5 and 10 kronor. 1000kr-notes are not very common in everyday life though. Beware if you get one, it may be fake. Better stay with the smaller ones.
Credit cards are accepted almost everywhere except maybe at small cafés.
Visa and Mastercard (MC) are the most common. American Express (Amex) is not always accepted.
There are plenty of ATM-machines in the city area, around the bigger attractions and malls. They thin out the farther you get from the city down-town area. Basically there are two kinds of ATMs, Swedbank (gray) and the other ones (usually blue). The banks have a cooperation going so that even if you have an account at Swedbank you may still withdraw cash from the blue ATMs. VISA and MC-cards are commonly accepted in both ATMs.
Euros are accepted at the bigger stores, but not always at a good rate.
Most well-known exchange offices are Forex (yellow signs) and the inconspicious Xchange (red signs). Most banks, the manned ones, can also exchange foreign currency.