What is the different between Server Side and Client Side?

I did a bit research, however I couldn't find the answer that I am satisfied. I started doing web development as hobby, and I would like to know what should I put on client side and what should I put on server side.

If I am not mistaken, the client side will give specific information back to user. While the client side is doing security and database. My apologies, if this wrong, however I would like at least a core understanding.

T. Wolf