The archipelago is sometimes also known as the East Indies, but some authorities apply a much broader meaning to this term by including Indochina, the Indian Subcontinent, and even areas as far west as Iranian Baluchistan.

The Malay Archipelago is the world's largest archipelago, and it encompasses many groups which may be considered archipelagoes in their own right. The major ones are:

• The Greater Sunda Islands
• The Lesser Sunda Islands
• The Maluku Islands
• The Philippines

The island group's area is more than 2 million km², and its total population is more than 300,000,000. The biggest islands in the archipelago are Borneo and Sumatra (New Guinea would be the biggest if it were included). The most heavily populated island is Java.

Together with Australia, the Malay Archipelago marks the traditional boundary between the Pacific Ocean to the east and the Indian Ocean to the west.

Geologically the archipelago is very interesting, being one of the most active vulcanological regions in the world. Geological uplifts in the region have also produced some impressive mountains, culminating in Mount Kinabalu in Sabah with a height of 4 101 m (or Puncak Jaya in Irian Jaya at 4 884 m, if New Guinea is included).

The climate throughout the archipelago, owing to its position astride the equator, is tropical. It is notably rainier in the west than in the east, however.

The region known as Maritime Southeast Asia is more or less coëxtensive with the Malay Archipelago, except that Singapore is not usually included in the latter.