Javanese

Three principal layers: ngoko (informal, intimate), madya (middle, polite), and krama (formal, deferential), with finer subdivisions for inflated honorific use. Switching levels means swapping the lexical word, not just the ending — 'eat' is mangan in ngoko, nedha in madya, dhahar in krama. Choosing the wrong level for the listener is a serious social misstep, and full mastery of krama is rare even among native speakers.

Yes, both are Austronesian — same family, different branches. Javanese is one of the major regional languages of Indonesia and many ethnic Javanese are bilingual in Indonesian (the national language) and Javanese. The two share many cognates and Indonesian has borrowed substantial vocabulary from Javanese, but they are not mutually intelligible without study.

Aksara Jawa is the traditional Javanese script, an abugida descended from the South Indian Brahmi family via earlier Indonesian scripts. It's been largely replaced by the Latin alphabet for daily use but remains taught in schools, used on street signs in some regions, and preserved in ceremonial and literary contexts. There's a slow but real revival movement for written Javanese.

Around 68 million native speakers, almost all on the Indonesian island of Java (especially Central Java, East Java, and parts of West Java's coast). Smaller communities live in Suriname (descendants of indentured workers brought during Dutch colonial rule), New Caledonia, and the Netherlands. It's the most-spoken Austronesian language by native speakers.

Easier than for most learners, harder than Indonesian-Malay. Cognates and shared structure give a head start, but Javanese's speech-level system has no Indonesian counterpart, the verb morphology is more elaborate, and the cultural calibration of register choice is a long-term skill. Many ethnic Javanese under 40 admit to limited krama fluency themselves.