Conjugation of Japanese Verbs and Adjectives
Japanese is a language whose modified forms of verbs and adjectives are created by joining additional unit of meanings (called morphemes) as suffix of words. It makes Japanese easier to learn, as there are much less irregular forms, or exceptions, such as what demonstrates in a language like English.
It is called conjugation for modifying a word from its basic form.
To get the modified forms of a word, you need to learn how to identify the stem of the word. From there, morphemes with different meanings can be attached to the stem.
For example, if you want to say do not eat in Japanese, you need the stem of the verb eat (食べ) and then attach not (ない) at it as a suffix to make it 食べない. This applies to many other modified forms such as ate, did not eat, must eat, must not eat, want to eat, do not want to eat, etc.