What is an open ended question?why do professionals ask open ended questions?

to know the real and hearts feeling,, comprehensively.

An open question can't have a clear and straight answer i.e YES or NO. It ask when we need to get some more details , how , when, where etc etc . This will open the forum for the discussion and conlusion rather then to have a sharp rejectection ot acceptance.

Open questions are the questions whose answer can not be yes or no, usually qustions will start with How, What instead of are/is it, do you?  In the other word, if you start an open question with your client, it will avoid a sharp reject from your client which exert more possibility on the outcomeof the conversation.

These are the questions to invite a discussion rather than expecting a definitive answer and a lot of that is being done here on the site.