What it means
当然 expresses that something is natural, logically expected, or unsurprising based on the situation. It can describe an outcome that follows from known facts, or a state that the speaker considers reasonable and unavoidable. It commonly appears as a predicate with だ or です, after a nominalized clause with のは, and before a noun in the form 当然の.
Usage note
当然 can sound firm because it presents the speaker's judgment as self-evident. In direct conversation, it may be perceived as dismissive if used to reject another person's surprise or concern. Do not confuse 当然の with 必ず; 当然の describes what is natural or expected, whereas 必ず expresses certainty that something will happen.
How to use it
その判断は当然です。
That decision is only natural.
当然の結果です。
It is a natural result.
静かなのは当然です。
It is only natural that it is quiet.
難しいのは当然です。
It is only natural that it is difficult.
彼が選ばれるのは当然です。
It is only natural that he is selected.
その判断は当然だ。
That decision is only natural.
当然の結果だ。
It is a natural result.
静かなのは当然だ。
It is only natural that it is quiet.
難しいのは当然だ。
It is only natural that it is difficult.
彼が選ばれるのは当然だ。
It is only natural that he is selected.