Although English is spoken throughout the island, the local people continue to speak their own Chamorro language. Some, particularly older residents who lived in Guam during the World War II period of Japanese occupation, speak Japanese, as well.

Native Guamanians, ethnically called Chamorros, are of basically Malayo-Indonesian descent with a considerable admixture of Spanish, Filipino, Mexican, and other European and Asian ancestries. Chamorros and other Micronesians constitute about half the population.

Due to three centuries of Spanish colonial rule, a significant proportion of vocabulary in Chamorro can be traced to Spanish and there is a fair amount of mutual intelligibility. However, Chamorro has nativized the use of many words from Spanish and it continues to use indigenous grammatical structures.

Don't be surprised if business owners and restaurant staff greet you with a hearty "Håfa Adai" (Chamorro for "Hello"). Give your best "Håfa Adai" to anyone you meet on your journey, or take an extra step and try out these simple Chamorro greetings.