You have to be able to identify yourself when you are travelling. You can do this with legitimate identification or your passport depending on where you are travelling. Be aware that some countries require you to have a visa.
When travelling outside the country you are required to identify yourself with either a passport or a national ID-card. If you posses a Swedish passport you can obtain more information from the police. In other cases contact your Embassy.
Travelling to certain countries requires a visa. Contact your travel agent or the destination country's embassy for more information about visas and how you can apply.
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