Japanese is the official language of Japan, where the majority of the citizens speak it as a first language. There are also millions of people who speak Japanese with some degree of proficiency outside of Japan-- predominantly Japanese descendants in Hawaii and Brazil.
The Japanese language has a number of dialects, some of which are mutually unintelligible. Thanks to the development of mass communications and the government’s directive to establish a common language, however, most people now speak a common tongue.
The Japanese language has absorbed a large number of foreign words from various other languages: Chinese (along with kanji) in the 6th to 9th centuries, Portuguese in the 16th century, and English after World War II. Today, 80 percent of loanwords are English and written in katakana. Examples include: maikaa (my car), taimingu (timing), konpyuutaa (computer), supiido (speed), and rasshu awaa (rush hour). English words that come from Japanese vocabulary include: tsunami, futon, sushi, judo, karate, karaoke, and honcho.
As you learn Japanese, you will come across some basic Japanese vocabulary words that sound like words in English. Hai is one example. It does not mean "hi!" In fact, it means "yes", and it is equivalent to an American saying "hmm" or "I see" in a conversational setting-- a verbal cue to let the speaker know that the listener is following along. (It is important to understand that hai does not necessarily mean that the listener agrees with the speaker!) Another example of a false friend is Ohayoo, the Japanese word for "Good morning," which sounds like the name of the state, Ohio.
Japanese has four different ways of addressing people. Kun is used for a younger man or a man of lower rank. Chan is for little children or intimate friends. San is universally used for almost anyone but children. Sama is very polite and is used when speaking to customers or VIPs. These titles are placed after a person's name.
Because of the nature of Japanese culture, which is characterized by a hierarchical system, the Japanese language has evolved to be very complicated. The style of speech varies significantly according to social class, gender, age, and so on. Only if you have personal information about your partner in conversation will you be able to choose the appropriate manner of speaking Japanese.
For instance, a man talking to his colleagues might say, "Ore ga kuu" (I eat), or more politely, "Boku ga taberu" (I eat). In a more formal situation, though, he would have to say, "Watashi ga tabemasu" (I eat). But even this is not polite enough if he is talking to people of superior rank. Then he will have to use a humble form for the verb "taberu" and an honorific form for the person he is addressing. The appropriate phrase would accordingly be, "Watakushi ga itadakimasu" (I eat) and "Tanaka-san ga meshiagarimasu" (Mr. Tanaka eats).
Believe it or not, he has not yet scaled the absolute summit of politeness! If he is talking to someone who requires the greatest respect, he will have to say, "Tanaka-sama ga omeshiagarini nararemasu" (Honorable Tanaka eats).