Japanese godan and ichidan verbs
The Japanese language has two main types of verbs: godan verbs, or quinquegrade verbs (五段動詞, godan-dōshi), and ichidan verbs, or unigrade verbs (一段動詞, ichidan-dōshi). == Terminology == Categories are important when conjugating Japanese verbs, since conjugation patterns vary according to the verb's category.
Source: Wikipedia — Japanese godan and ichidan verbs (CC BY-SA 4.0)