A realis mood is a grammatical mood which is used principally to indicate that something is a statement of fact; in other words, to express what the speaker considers to be a known state of affairs, as in declarative sentences. Most languages have a single realis mood called the indicative mood, although some languages have additional realis moods, for example to express different levels of certainty. By contrast, an irrealis mood is used to express something that is not known to be the case in reality.An example of the contrast between realis and irrealis moods is seen in the English sentences "He works" and "It is necessary that he work". In the first sentence works is a present indicative (realis) form of the verb, and is used to make a direct assertion about the real world. In the second sentence work is in the subjunctive mood, which is an irrealis mood – here that he work does not express (necessarily) a fact about the real world, but refers to what would be a desirable state of affairs.However, since mood is a grammatical category, referring to the form a verb takes rather than its meaning in a given instance, a given language may use realis forms for a number of purposes other than their principal one of making direct factual statements. For example, many languages use indicative verb forms to ask questions (this is sometimes called interrogative mood) and in various other situations where the meaning is in fact of the irrealis type (as in the English "I hope it works", where the indicative works is used even though it refers to a desired rather than real state of affairs). The indicative might therefore be defined as the mood used in all instances where a given language does not specifically require the use of some other mood.Realis mood and indicative mood can be indicated by the respective glossing abbreviations REAL and IND.