What exactly are “polar questions” in English Grammar?

[Amerikanerin]

Greetings:
What exactly are “polar questions” in English Grammar? I think that they have something to do with questions words like where, when, why, how, what but I am not exactly sure of the exact properties of polar questions? Finally, why exactly are they called “polar” questions? Do they have something to do with a certain kind of bear? Thank you and I look forward to your postings.

[MLS]

These questions are questions you have to answer with either yes or no and which are thus sometimes called yes-no questions.

[Deccius]

Finally, why exactly are they called “polar” questions? Do they have something to do with a certain kind of bear? Thank you and I look forward to your postings.

No, polar questions have nothing to do with polar bears. Polar questions are called thus, because the expected answer is polarized (divided) into two choices: either "yes" or "no".