Verbs, like people, have moods—three, in fact: indicative, imperative and subjunctive. And like people’s moods, verb moods reveal attitudes: specifically, the writer’s or speaker’s attitude about what is being said.
Is the writer or speaker stating a fact or opinion, or asking a question (indicative)? Giving a command or a direction (imperative)? Expressing a suggestion, requirement or desire, or stating an imaginary or hypothetical condition (subjunctive)? The verb moods will tell you.
If you think you are up to the challenge, try to identify the mood of the verbs in square brackets in the following sentences.