If you are visiting Denmark you must check whether you need a visa, depending upon your nationality and the purpose of your visit.
There are no tourist visa requirements for nationals of (e.g.) the USA, Canada, Japan, Australia, New Zealand, Argentina, Brazil, Singapore, Malaysia and Mexico.
If you are coming from a not-European country, you can consult the local Danish embassy and get more information here.
Denmark is a member of the European Union`s Schengen agreement, which essentially means that passport controls have been eliminated between Schengen countries in Europe. So a Schengen visa normally grants you the right to travel in the Schengen region for maximum 90 days.
Therefore, you don`t have to stop or show a passport, if you are travelling between Denmark and Sweden and Denmark and Germany. You still have to bring your passport in case you need to prove your identity.
Following countries is a member of the European Union Schengen agreement:
Austria, Belgium, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden and Switzerland.
If you are entering Denmark from a country outside the Schengen area, you can expect passport control. Travellers from outside the Schengen agreement area may also need to require a visa. Check out the related links, if you are from a country, where you will need a visa to enter Denmark.