The English language contains several moods for verbs, which indicate the speaker's or writer's attitude toward the recipient of the message. The imperative mood is used to indicate a command, or to grant permission. Sentences in the imperative mood are almost always in the second person, meaning that the speaker or writer is directly addressing someone.
Unlike other second person sentences which explicitly state the subject word "you," the imperative form does not use a subject. Instead, the subject is implied, and is referred to as the "understood subject". The main exception is the first person plural imperative sentence, which contains the subject "let us", or "let's".
The other exception involves the speaker dictating that an action be carried out by a third party. In this case, the verb "let" begins the sentence, followed by the third person subject, "him", "her", or "them". In this case, the command "Read the letter," would become "Let him read the letter." Imperative sentences using the first person plural or third person are more rare than second person imperative statements, however.
Under English morphology, the verb form of the imperative mood is just the bare infinitive. This form is the same as the second person indicative conjugation, except for the verb "be". In the imperative form, sentences using the verb "to be" do not use "are", but simply use "be", as in the command "Be quiet!"
As mentioned, the imperative mood can convey directions, prohibitions, orders, permission, and suggestions. Statements such as "Come in," "Include a check with your order," or even "Behave!" are all examples of sentences using this mood. To form a negative sentence in the imperative mood, the sentence uses the auxiliary verb "do" and the negative particle "not". Thus, the negative form of "Shut the door!" becomes "Do not shut the door!"
Many statements that could be made in the imperative are often made in the indicative form instead. For example, most people will say "Could you come here for a minute?" rather than "Come here for a minute!" The reason for this is that the imperative mood can appear impolite, depending on the context and situation.
Direct speech acts with the imperative can be interpreted as violating a person's personal territory. Therefore, indirect speech acts using the indicative mood are more often used for requests. The imperative mood, when used to convey a request instead of an order, is often followed with the word "please" to denote respect for the audience.