Denmark's national language is Danish, a member of the Germanic branch of the group of Indo-European languages, and within that family, part of the North Germanic, East Norse group. It is, in theory, very similar to Norwegian Bokmål and also to Swedish, and is to some extent intelligible to speakers of those languages, especially in written form. However its sound is more influenced by the guttural German language, rather than the lilting languages found to the north and understanding spoken Danish may be a trace more difficult to those who only speak Swedish or Norwegian. It is also more distantly related to Icelandic and Faroese, though spoken Danish is not mutually intelligible with these languages.

English is widely spoken in Denmark, the only partial exception is children or people older than 65. Danish school children start their English lessons in third grade, and regular English lessons continue until students finish high school, furthermore many Danish university courses are fully or partially taught in English. In this regard it is worth noting that Denmark is probably one of very few countries in the world, where you don't get extra points for trying to speak the language, and Danes in general have very little patience with non-fluent speakers. So except for a few words like Tak (Thank you) or Undskyld mig (Excuse me), English-speakers are much better off just speaking English than fighting their way through a phrasebook. If you do try, and the person you are talking to immediately switches to English, don't feel bad, it is not meant to condescend or belittle. Should you perceive it so, you can take minor comfort when the conversation stops every once in a while as the person you're talking to skims their mental dictionary, looking for an English equivalent of a Danish word. You might also encounter some wacky English grammar once in a while among the very young or the slightly older generation. Though this generally shouldn't a problem, just keep in mind that enunciating just a tiny bit when speaking will go a long way in abating such situations. Also of note, the Danish language has no equivalent to the English word please, so at times it may seem as though Danes are rude when speaking English. This is not their intention, but simply results from them directly translating from Danish to English.

Many Danes also speak German, and it is widely spoken in areas that attract many tourists from Germany, i.e. mainly the Jutland West Coast, the southern part of Funen and nearby islands (e.g. Langeland and Ærø), and also in Southern Jutland (Sønderjylland / Northern Schleswig). Elsewhere in the country, many people vehemently prefer to avoid speaking it, even when they do have some command of the language, and you'll have a hard time convincing anyone (outside the tourist industry) otherwise - this has nothing to do with history, but is merely a result of the high fluency in English, making the locals less inclined to struggle through a language they are not entirely comfortable with - in a pinch or emergency though, people will probably step up, and do their best to help. French is also spoken to some degree, as all Danish students have received at least 3 years of lessons in either German or French, but given the Danes limited contact with the French language, fluency tends to be lagging.

Bring your own unlocked GSM phone to make calls. Prepaid SIM cards are available at most shops and international calling can be reasonably priced. The prepaid credit generally only work in Denmark, but can be purchased in small amounts to avoid waste when you leave.