A question may be either a linguistic expression used to make a request for information

Information

Information in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...

, or else the request itself made by such an expression. This information may be provided with an answer

Answer

Generally, an answer is a reply to a question or is a solution, a retaliation, or a response that is relevant to the said question.In law, an answer was originally a solemn assertion in opposition to some one or something, and thus generally any counter-statement or defense, a reply to a question...

.

Questions are normally put forward or asked using interrogative sentences

Sentence (linguistics)

In the field of linguistics, a sentence is an expression in natural language, and often defined to indicate a grammatical unit consisting of one or more words that generally bear minimal syntactic relation to the words that precede or follow it...

. However they can also be formed by imperative

Imperative mood

The imperative mood expresses commands or requests as a grammatical mood. These commands or requests urge the audience to act a certain way. It also may signal a prohibition, permission, or any other kind of exhortation.- Morphology :...

 sentences, which normally express commands: "Tell me what two plus two is"; conversely, some expressions, such as "Would you pass the salt?", have the grammatical form of questions but actually function as requests for action, not for answers, making them allofunctional.