U-WEIRDO Verbs:
Categoría #1 (Volition/Causation/Influence)
Categoria #2 (Emotion, feeling, judgement)
Categoría #3 (Doubt, Denial, Disbelief & Impersonal Expresssions of Doubt, Denial, Disbelief)

 
What is meant by "mood?

In addition to the various tenses, verbs can exist in three moods.  Mood refers to the attitude of the speaker toward the action/condition of the verb.
There are three moods: They are the ...

1. indicative mood: used to express or indicate facts, real information.
2. imperative mood: used to express a command.
3. subjunctive mood: used to express a potential fact. It stresses the speaker's feeling about the fact and is "subjective" (contrary to fact statements) about these facts.

So, verbs can be in one of the three moods.
1.  The Indicative mood is used to indicate facts.  This is the most common mood, and most of the verb forms that you use in everyday conversation belong to the indicative mood.  The present tense, the past tense, the future tense, etc.. are all examples of tenses in the indicative mood.

• Robert is here.
• Robert was here.
• Robert will be here tomorrow.

2.  The imperative mood is used to express a command.  This mood is not divided into tenses.

• Robert, study Spanish now!
• Robert, be home on time!

3. The subjunctive mood is used to express an attitude or feeling. It stresses feelings about the fact or the idea.  The speaker is subjective about it.

• The school requires that Robert study Spanish.
• I wish that Robert was here.
• The teacher recommends that Robert do his homework.