Difference between "fee" and "fees" [closed]

Which is correct: What is the course fee? or What is the course fees? Also, are the two words fee and fees interchangeable?

The verb and noun should agree in number, so "What is the course fee?" and "What are the course fees?" are the options. In most cases, either expression may be used. It is normal at a golf course, for example, for there to be be one fee that covers all usage, but it is also likely that there are different fees that cover different aspects of usage (e.g. an entrance fee and a maintenance fee). Since you presumably won't know the fee structure before asking, you can choose freely how to form the question.