Knowledge?

What does having knowledge mean? How should I understand I know something? Is it only observable when I apply that knowledge? Is it the application that shows the extend of someone's knowledge? What kind of application? I’m lost in the point that I can’t understand the true nature and this ability. What does it do when we learn facts? I know so many psychological, sociological, biological, chemical, etc. theories. But I don’t know if any of them will help mere survival. 

This is a rather odd topic to be asked by a student, student who dedicated his life to gain perfect marks. I hate to say it, but that is my goal in life. I want to have good grades, I need to have good grades. I like studying but thats not my reason. 

I can’t believe that less than couple of years ago I devalued academic success, but now it’s all I want!!!!!! 

Unfortunately it is the only way to become what I like to be!

Good luck!...