The Austronesian languages are a language family that is widely dispersed throughout Maritime Southeast Asia, Madagascar and the islands of the Pacific Ocean, with a few members in continental Asia. Austronesian languages are spoken by about 386 million people, making it the fifth-largest language family by number of speakers, behind only the Indo-European languages, the Sino-Tibetan languages, the Niger-Congo languages, and the Afroasiatic languages. It is on par with Indo-European, Niger–Congo, and Afroasiatic as one of the best-established language families. Major Austronesian languages with the highest number of speakers are Malay (Indonesian and Malaysian), Javanese, and Filipino (Tagalog). The family contains 1,257 languages, which is the second most of any language family. 

Similarities between the languages spoken in the Malay Archipelago and the Pacific Ocean were first observed in 1706 by the Dutch scholar Adriaan Reland. In the 19th century, researchers (e.g. Wilhelm von Humboldt, Herman van der Tuuk) started to apply the comparative method to the Austronesian languages, but the first comprehensive and extensive study on the phonological history of the Austronesian language family including a reconstruction of Proto-Austronesian lexicon was made by the German linguist Otto Dempwolff. The term Austronesian itself was coined by Wilhelm Schmidt (German "austronesisch") which comes from Latin "auster" "south wind" plus Greek "nêsos" "island". The family is aptly named, as the vast majority of Austronesian languages are spoken on islands: only a few languages, such as Malay and the Chamic languages, are indigenous to mainland Asia. Many Austronesian languages have very few speakers, but the major Austronesian languages are spoken by tens of millions of people and one Austronesian language, Malay (including Indonesian and Malaysian), is spoken by 250 million people, making it the 8th most spoken language in the world. Approximately twenty Austronesian languages are official in their respective countries (see the list of major and official Austronesian languages).
When were similarities between the languages first noticed?
1706