Japanese (日本語) "Nihon-go" or "Nippon-go" in Japanese) is the language spoken in Japan, in East Asia. A theory about its origin is that Japanese, Mongolian, and Turkish come from the same family of Altaic languages. Interestingly, a different term is used for Japanese as a course of study by citizens: it is "kokugo" (国語), which means national language.
In English, the order of the words is very important. For example, the sentences "Is it?" and "It is." mean different things. In Japanese a lot of these differences are made by adding or changing the endings of words. So a Japanese word has a stem called a "body", and additional parts (called suffixes). By changing the suffix you can change the meaning of the word.