Scandinavia proper consists of Norway, Sweden and Denmark, of which the former two lie on the Scandinavian peninsula.
In English, the term "Scandinavia" is often used to refer to the Nordic countries, which in addition to these three include Finland and Iceland, and the autonomous Faroe Islands, Greenland and Åland. This use is much less common in the Nordic countries themselves. Svalbard and Jan Mayen belong to Norway, but they are not on the Scandinavian Peninsula and are special cases also otherwise.
The Nordic countries share a common history (see Nordic history), their societies resemble each other, and they have far-reaching cooperation, such as a passport union dating back to the 1950s.