Wh-question

A question is a linguistic expression used to make a request for information, or the request made using such an expression. The information requested is provided in the form of an answer.

Questions have developed a range of uses that go beyond the simple eliciting of information from another party. Rhetorical questions, for example, are used to make a point, and are not expected to be answered. Many languages have special grammatical forms for questions (for example, in the English sentence "Are you happy?", the inversion of the subject you and the verb are shows it to be a question rather than a statement). However, questions can also be asked without using these interrogative grammatical structures – for example one may use an imperative, as in "Tell me your name".

The principal use of questions is to elicit information from the person being addressed by indicating the information which the speaker (or writer) desires. However, questions can also be used for a number of other purposes. Questions may be asked for the purpose of testing someone's knowledge, as in a quiz or examination. Raising a question may guide the questioner along an avenue of research (see Socratic method).

A research question is an interrogative statement that manifests the objective or line of scholarly or scientific inquiry designed to addresses a specific gap in knowledge. Research questions are expressed in a language that is appropriate for the academic community that has the greatest interest in answers that would address said gap. These interrogative statements serve as launching points for the academic pursuit of new knowledge by directing and delimiting an investigation of a topic, a set of studies, or an entire program of research.

A rhetorical question is asked to make a point, and does not expect an answer (often the answer is implied or obvious). Some questions are used principally as polite requests, as with "Would you pass the salt?"

...
Wikipedia