English: Replicas/recon structed copies of Norwegian viking era/medieval type long ships moored to the pier in the harbour of Tønsberg, Norway. In the background is the Kaldnes bro footbridge across the Byfjorden.

The types of Viking ships were quite varied, depending on what the ship was intended for, but they were generally characterized as being slender and flexible boats, with symmetrical ends with true keel. They were clinker built, which is the overlapping of planks riveted together.

In the literature, Viking ships are usually seen divided into two broad categories: merchant ships and warships. These categories are overlapping; some kinds of merchant ships, built for transporting cargo specifically, could also be used as warships. The majority of Viking ships were designed for sailing rivers, fjords and coastal waters, while a few types, such as the knarr, could navigate the open sea and even the ocean. The Viking ships ranged from the Baltic Sea too far from the Scandinavian homelands, to Iceland, the Faroe Islands, Greenland, Newfoundland, the Mediterranean, the Black Sea and Africa.

The long-ship is characterized as a graceful, long, narrow, light, wooden boat with a shallow draft hull designed for speed. Longships were fitted with oars along almost the entire length of the boat itself. Later versions sported a rectangular sail on a single mast which was used to replace or augment the effort of the rowers, particularly during long journeys.

The most common way to classify longships is by the number of rowing positions on board. Types ranged from the Karvi, with 13 rowing benches, to the Busse, one of which has been found with an estimated 34 rowing positions.