Understanding OG tags og:title, og:description, etc.,

Can someone please explain what the purpose of og is for? I've searched and it seems like it has something to do with social media - Facebook to be specific. I see og:title, og:description, when I view the source of my webpage. Is this for social media only?

This is what I have on my site;

<meta property="og:description" content="page content is here"/>

My site does not have a "meta name="description" do I need that even if I already have og:description?