National id-cards are accepted in 22 out of the EU’s 27 countries, which make up the so called Schengen agreement, as well as Norway, Iceland and Switzerland. The United Kingdom, Ireland and summer destinations like Cyprus, Bulgaria and Rumania are not part of this agreement. You will still need your passport there. A Swedish national id-card costs SEK 400 and can be obtained from the police authorities. Read more at www.polisen.se/Service/Pass-och-id-kort