A Yes/No Question is a question that can be answered with yes or no. They normally begin with an auxiliary verb or a modal verb.

Questions with question words in the Present Progressive
Question word   Auxiliary  Answer
What   | are |  I am working on my computer.
Where   | is |   He is going to the pet shop.
Why   | are |   They are carrying the buckets because they want to clean their bikes.

For me YES/NO questions are one of the basic ways of communicating in the English language.

Although it seems so simple there are some grammatic rules that are confusing, also for someone whose first language is English. For example, we have the “Do” and “Does” questions, which are usually answered with YES and NO. The thing is, that Do and Does have their own rule when used in a sentence. DO is used with first and second person while DOES is used with third person.  You can say Does she eat meat?  but you can´t say Does you eat mat? In a way its understandable if you someone told you that, but it is Grammatically incorrect, As so go for the rules when asking questions beginning with am, is, are, have, has ,can, could, will, would, may, might, shall and must.