Northern Europe is a term for the northern part of Europe, though its precise boundaries are vague and defined variously. It is a term that groups the Nordic countries (which are present in all definitions):

• Denmark, Finland, Iceland, Norway and Sweden, as well as Åland, the Faroe Islands, Jan Mayen and Svalbard. (Though politically and historically closely tied to Northern Europe, the Nordic territory of Greenland is nevertheless geographically closer to the continent of North America.)

• The Baltic states: Estonia, Latvia, and Lithuania.
• The British Isles: Great Britain, the Channel Islands and the Isle of Man (see also Western Europe).
• Ireland
• Areas bordering, or in close proximity to, the Baltic Sea and the North Sea, i.e. north-western Russia (including Kaliningrad), northern Poland, northern Germany, the Netherlands, Belgium, Luxembourg, and the French region of Nord-Pas de Calais.
• Occasionally Ingria, Karelia and the Kola Peninsula (see also Eastern Europe).

The United Nations defines Northern Europe as:

• (Finland)
• Channel Islands: and
• (Denmark)
• Republic Of Ireland
• Svalbard and Jan Mayen (Norway)

Before the 19th century, the term 'Nordic' or 'Northern' was commonly used to mean Northern Europe in a sense that included the Nordic countries, European Russia, the Baltic countries (at that time Livonia and Courland) and Greenland.

In earlier eras, when Europe was dominated by the Mediterranean region (i.e. the Roman Empire), everything not near this sea was termed Northern Europe, including Germany, the Low Countries, and Austria. This meaning is still used today in some contexts, such as in discussions of the Northern Renaissance. In medieval times, the term (Ultima) Thule was used to mean a semi-mythical place in the extreme northern reaches of the continent.

Today the term is of subjective nature with its meaning usually determined by the geo-political outlook of the speaker. This also means that the definition of the term is largely socio-political as there is no rationale to include Great Britain as being part of Northern Europe while excluding the Netherlands.