A mood shows the writer’s attitude toward what he/she is saying.
Indicative Mood states an actuality or fact.
Example:
Imperative Mood makes a request.
Example:
Subjunctive Mood expresses a doubtful condition (contrary to fact) and is often used with an "if" clause.
Example:
The following verbs often attract the subjunctive mood: ask, recommend, suggest, wish, insist, order, commend, request, and demand. A verb in the subjunctive mood may have a different form. The subjunctive for the present tense third-person singular drops the s or es so that it looks and sounds like the present tense for everything else. In the subjunctive mood, the verb to be is be in the present tense and were in the past tense, regardless of what the subject is.
Example:
(The verb follows ‘if’ and expresses a non-factual condition.)
(The second verb is in a clause following a verb expressing a wish. It suggests a non-factual or doubtful condition.)