Difference between client ID and Client secret in Linked application

I am newbie in development field. So, asking a childish question. I want to integrate LinkedIn in my website for login. So, I created an application in linkedIn. Then, I got client ID and Client secret as Authentication Keys. Can you please explain the difference between them? Why should we not share Client secret? What can happen if i share it? What is the exact use of Client ID and client secret keys? If you have any reference links, please share it with me too. Thank you in advance .