What does remark means and When I use it?

Remark

I get this question a lot when I use it in daily conversation. It's subtle to explain what is different between "say" and "remark". 

When you say something as an opinion

The word "Remark" is usually used to say about your opinion or say something being used that is related to the current situation.

Tom remarked "There is no private data. We type something, search for something, and all of it is sent to Google." against Google News. 

Do you understand what the word remark is? If you don't understand it, I'll show examples more.

 Tommy always remarks "Recycling Campaign" when we are throwing away something.