Deontic modality

Deontic modality (abbreviated ) is a linguistic modality that indicates how the world ought to be according to certain norms, expectations, speaker desire, etc. In other words, a deontic expression indicates that the state of the world (where 'world' is loosely defined here in terms of the surrounding circumstances) does not meet some standard or ideal, whether that standard be social (such as laws), personal (desires), etc. The sentence containing the deontic modal generally indicates some action that would change the world so that it becomes closer to the standard or ideal.
This category includes the following subcategories:
A related type of modality is dynamic modality, which indicates a subject's internal capabilities or willingness as opposed to external factors such as permission or orders given.
Realisation in speech.
Deontic moods are a category of grammatical moods that are used to express deontic modality. An example for a deontic mood is the imperative ("Come!").
However, many languages (like English) have additional ways to express deontic modality, like modal verbs ("I "shall" help you.") and other verbs ("I "hope" to come soon."), as well as adverbials ("hopefully") and other constructions.
Esperanto.
Esperanto has a mood called "volitive" which is really a generic deontic mood, expressing commands as well as will, desire, and purpose. It is formed by adding -u to the verb stem.