他動詞(たどうし)・自動詞(じどうし)Done through action vs. occurring on its own

The two most fundamental divisions that can be made with Japanese verbs are transitive verbs - the subject is moving/acting upon something else, and intransitive verbs - the subject themself is moving/acting. Sometimes these terms are simplified even further to 'other-move' (transitive), and 'self-move' (intransitive).

Basically, this is the difference between verbs that require an object marked with を (transitive verbs), and those that only require が, to show that the subject itself is moving (intransitive).

In Japanese, there are many transitive/intransitive pairs of verbs, and these will need to be memorized.

Fun Fact

In Japanese, the two ways in which all verbs can be described are an act/motion (動作(どうさ)), and an act/motion upon something (作用(さよう)).

Fun Fact

Although they are not traditionally grouped this way, する and なる may also be thought of as a transitive/intransitive pair. This is due to する always implying that something is being controlled (acted upon), while なる always implies that something happens on its own, or cannot be controlled.